refactor: migrate templates/ → registry/examples/ (heygen-com#253)

## What

PR 2/17 of the catalog system rollout. **Physical directory rename.** Stacks on heygen-com#252.

- `git mv templates/ registry/examples/` — all 8 example directories (`decision-tree`, `kinetic-type`, `nyt-graph`, `play-mode`, `product-promo`, `swiss-grid`, `vignelli`, `warm-grain`) plus `templates.json`
- `packages/cli/src/templates/remote.ts` — `TEMPLATES_DIR` constant from `"templates"` → `"registry/examples"`, exported for regression testing
- `scripts/generate-template-previews.ts` — `remoteTemplatesDir` resolved to the new path
- Comment updates in `packages/cli/src/templates/generators.ts` and `packages/cli/src/commands/init.ts`
- New regression test `packages/cli/src/templates/remote.test.ts` pinning the path constants so future reverts fail a test instead of silently breaking installed CLIs

Design doc: [Hyperframes Catalog System](https://www.notion.so/heygen/Hyperframes-Catalog-System-Design-Plan-341449792c69813f899dcd53b4c0383a).

## Why

The current `templates/` directory is a flat "things that scaffold projects" bucket. The catalog model splits content into three tiers: **examples** (full projects — what today's templates are), **blocks** (sub-compositions), and **components** (effect snippets). `registry/examples/` is the canonical home for what was previously at `templates/`, and this PR makes room for `registry/blocks/` and `registry/components/` in future PRs without top-level clutter.

## How

- `git mv` preserves file history — GitHub renders these as renames, not deletions + additions.
- Remote template fetch via giget reads `TEMPLATES_DIR`, so updating that one constant is sufficient for the CLI's remote code path.
- The CLI's **internal** `packages/cli/src/templates/` directory (which holds the `blank` and `_shared` bundled assets plus `generators.ts`/`remote.ts`) is a separate concept and is **not** touched here. Renaming that module belongs to PR 3 where the abstraction changes to a registry resolver.
- `templates.json` keeps its existing shape and location (now at `registry/examples/templates.json`). **PR 3 will transform it** to the new `registry.json` shape introduced in PR 1 and generate a per-item `registry-item.json` for each example. Leaving the shape change to PR 3 keeps this PR a pure physical move.

## ⚠️ Breaking change for previously-installed CLIs (`hyperframes@0.1.0` – `0.3.0`)

**What happens:** every published CLI version has `TEMPLATES_DIR = "templates"` baked in. After this PR lands on `main`, those CLIs will 404 on:

- `raw.githubusercontent.com/heygen-com/hyperframes/main/templates/templates.json` (manifest list) — caught silently in `listRemoteTemplates`, so the template picker falls back to showing only `blank`
- `github:heygen-com/hyperframes/templates/<id>#main` (giget download) — raises "Template downloaded but missing index.html"

**Decision: accept the break.** Hyperframes is pre-1.0 OSS with a small installed base; complex mitigations (dual-path fetch, redirect stubs, manifest-at-old-path with empty array) add permanent maintenance cost for a one-time rename.

**Rollout plan:**

1. Merge heygen-com#252 (PR 1 — types & schemas) first
2. Merge this PR (heygen-com#253)
3. Ship a patched CLI release (`hyperframes@0.3.1`) in the same work-day. Already-pinned old CLIs break on remote examples, but upgrading restores full functionality
4. Note the break in release notes + `CHANGELOG.md` under the `0.3.1` entry

Users still on an older CLI will see the failure only if they invoke `hyperframes init` with `--template <non-blank>`; `--template blank` (bundled) continues to work offline on every version.

## Test plan

- [x] `bun run test` in `packages/cli`: **57 passed** (was 55 on main, +2 regression tests for the path constants). Same 4 pre-existing failures (SRT/VTT whisper normalizer + `lintProject` clean-project test) — unchanged from main. No regressions
- [x] **Manual smoke test**: `hyperframes init /tmp/x --template blank` works (bundled code path, unchanged)
- [x] `bunx oxfmt --check` + `bunx oxlint`: clean
- [x] `bun run typecheck` (core + studio, pre-commit hook): clean
- [ ] **Manual smoke test for remote fetch (`--template warm-grain`)** — not verifiable locally before merge. Remote fetch resolves `github:heygen-com/hyperframes/registry/examples/<id>#main`, which doesn't exist until this PR lands. Will work on `main` immediately after merge.

## Breaking / migration

- Internal repo path changes only. `--template` CLI flag continues to accept the same template names.
- See "Breaking change for previously-installed CLIs" above — decision is to ship a simultaneous CLI release rather than add a compat shim.

## Commits

1. `d691bd1` — initial rename + CLI path constant update
2. `fc0c642` — review feedback: docstring fix, regression tests, clarifying comment in `init.ts`, export constants for testing

## Stacks on

heygen-com#252 — base branch. When heygen-com#252 merges, this rebases onto `main`.

## Next in stack

PR 3 — `feat(cli): registry resolver + installer`. Transforms `templates.json` to the new `registry.json` shape (from PR 1's schema), generates `registry-item.json` for every existing example, introduces `packages/cli/src/registry/{resolver,installer,remote}.ts`, renames the `packages/cli/src/templates/` CLI module, and refactors `init` to call through the new abstraction.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Author: jrusso1020

packages/cli/src/commands/init.ts

@@ -156,6 +156,10 @@ function resolveAssetDir(devSegments: string[], builtSegments: string[]): string
   return existsSync(devPath) ? devPath : builtPath;
 }
 
+// Resolves bundled templates shipped inside the CLI package
+// (packages/cli/src/templates/<id> in dev, dist/templates/<id> when packed).
+// Not to be confused with the repo-root registry/examples/ directory, which
+// is fetched remotely via fetchRemoteTemplate.
 function getStaticTemplateDir(templateId: string): string {
   return resolveAssetDir(["..", "templates", templateId], ["templates", templateId]);
 }

packages/cli/src/templates/generators.ts

@@ -21,7 +21,7 @@ export const BUNDLED_TEMPLATES: TemplateOption[] = [
 
 /**
  * Resolve the full template list by merging bundled and remote templates.
- * Fetches templates.json from GitHub (cached 24h). No CLI release needed to add templates.
+ * Fetches `registry/examples/templates.json` from GitHub (cached 24h). No CLI release needed to add templates.
  * If offline, returns only bundled templates.
  */
 export async function resolveTemplateList(): Promise<TemplateOption[]> {

packages/cli/src/templates/remote.test.ts

@@ -0,0 +1,15 @@
+import { describe, expect, it } from "vitest";
+import { MANIFEST_FILENAME, TEMPLATES_DIR } from "./remote.js";
+
+// These constants construct the GitHub URL that installed CLIs use to fetch
+// remote examples. Accidentally reverting either value silently breaks init
+// for every user. Pin them explicitly.
+describe("remote template path constants", () => {
+  it("TEMPLATES_DIR points to registry/examples", () => {
+    expect(TEMPLATES_DIR).toBe("registry/examples");
+  });
+
+  it("MANIFEST_FILENAME is templates.json (renamed to registry.json in PR 3)", () => {
+    expect(MANIFEST_FILENAME).toBe("templates.json");
+  });
+});

packages/cli/src/templates/remote.ts

@@ -2,16 +2,17 @@
  * Remote Template Fetching
  *
  * Downloads templates from the hyperframes GitHub repository using giget.
- * Templates live in the `templates/` directory of the repo.
+ * Templates live in the `registry/examples/` directory of the repo.
  */
 
 import { existsSync, readFileSync, writeFileSync, mkdirSync } from "node:fs";
 import { join } from "node:path";
 import { homedir } from "node:os";
 
 const REPO = "heygen-com/hyperframes";
-const TEMPLATES_DIR = "templates";
-const MANIFEST_FILENAME = "templates.json";
+// Exported for regression testing — see remote.test.ts.
+export const TEMPLATES_DIR = "registry/examples";
+export const MANIFEST_FILENAME = "templates.json";
 
 /** Cache directory for remote template metadata. */
 const CACHE_DIR = join(homedir(), ".hyperframes", "cache");
@@ -71,7 +72,7 @@ export async function listRemoteTemplates(): Promise<RemoteTemplateInfo[]> {
 
 /**
  * Download a template from GitHub into destDir using giget.
- * Fetches from `examples/<templateId>` in the hyperframes repo.
+ * Fetches from `registry/examples/<templateId>` in the hyperframes repo.
  */
 export async function fetchRemoteTemplate(
   templateId: string,