refactor(core): replace cheerio with linkedom to drop deprecated whatwg-encoding (heygen-com#187)

## Summary

- `cheerio` pulls `encoding-sniffer` → `whatwg-encoding@3.1.1` (deprecated), causing a warning on every `npm install -g hyperframes`
- `linkedom` was already bundled into the CLI via tsup `noExternal` and has zero deprecated transitive deps
- Rewrote `htmlBundler.ts` and `subComposition.ts` to use standard DOM APIs via `linkedom`
- Added a `parseHTMLContent` helper that wraps HTML fragments in a full document structure (required for `linkedom` to populate `document.body`)
- Removed `cheerio` from `cli` dependencies and tsup `external` list
- Replaced `cheerio` with `linkedom` in `core` `optionalDependencies`

## Test plan

- [x] All 411 tests pass (`bun run test` in `packages/core`)
- [x] Full monorepo build succeeds (`bun run build`)
- [x] TypeScript typecheck passes

Author: miguel-heygen

.claude/settings.json

@@ -8,7 +8,7 @@
             "type": "command",
             "timeout": 180,
             "statusMessage": "Running build + lint + typecheck before commit…",
-            "command": "node -e \"\nconst chunks = [];\nprocess.stdin.on('data', d => chunks.push(d));\nprocess.stdin.on('end', () => {\n  const input = JSON.parse(Buffer.concat(chunks).toString());\n  const cmd = input.tool_input?.command || '';\n  if (!/git\\\\s+commit\\\\b/.test(cmd)) process.exit(0);\n  const { execSync } = require('child_process');\n  const cwd = process.env.PWD || process.cwd();\n  const steps = [\n    ['bun run build', 'Build'],\n    ['bun run lint', 'Lint'],\n    ['bun run --filter \\'*\\' typecheck 2>&1 | grep -v \\'vitest\\\\|test\\\\.ts\\' || true', 'Typecheck'],\n  ];\n  const failures = [];\n  for (const [script, label] of steps) {\n    try { execSync(script, { cwd, stdio: 'pipe' }); }\n    catch (e) {\n      failures.push(label + ':\\\\n' + (e.stdout?.toString() || e.message).slice(0, 400));\n    }\n  }\n  if (failures.length > 0) {\n    process.stdout.write(JSON.stringify({\n      continue: false,\n      stopReason: '\\u274c Pre-commit checks failed:\\\\n\\\\n' + failures.join('\\\\n\\\\n') + '\\\\n\\\\nFix the issues above before committing.',\n    }));\n  }\n});\""
+            "command": "node -e \"\nconst chunks = [];\nprocess.stdin.on('data', d => chunks.push(d));\nprocess.stdin.on('end', () => {\n  const input = JSON.parse(Buffer.concat(chunks).toString());\n  const cmd = input.tool_input?.command || '';\n  if (!/git\\\\s+commit\\\\b/.test(cmd)) process.exit(0);\n  const { execSync } = require('child_process');\n  const cwd = execSync('git rev-parse --show-toplevel', { encoding: 'utf8' }).trim();\n  const steps = [\n    ['bun run build', 'Build'],\n    ['bun run lint', 'Lint'],\n    ['bun run --filter \\'*\\' typecheck 2>&1 | grep -v \\'vitest\\\\|test\\\\.ts\\' || true', 'Typecheck'],\n  ];\n  const failures = [];\n  for (const [script, label] of steps) {\n    try { execSync(script, { cwd, stdio: 'pipe' }); }\n    catch (e) {\n      failures.push(label + ':\\\\n' + (e.stdout?.toString() || e.message).slice(0, 400));\n    }\n  }\n  if (failures.length > 0) {\n    process.stdout.write(JSON.stringify({\n      continue: false,\n      stopReason: '\\u274c Pre-commit checks failed:\\\\n\\\\n' + failures.join('\\\\n\\\\n') + '\\\\n\\\\nFix the issues above before committing.',\n    }));\n  }\n});\""
           }
         ]
       }

bun.lock

@@ -28,7 +28,6 @@
     "@hono/node-server": "^1.8.0",
     "@puppeteer/browsers": "^2.13.0",
     "adm-zip": "^0.5.16",
-    "cheerio": "^1.2.0",
     "citty": "^0.2.1",
     "compare-versions": "^6.1.1",
     "esbuild": "^0.25.0",
@@ -49,7 +48,6 @@
     "@types/mime-types": "^3.0.1",
     "@types/node": "^22.0.0",
     "adm-zip": "^0.5.16",
-    "cheerio": "^1.2.0",
     "hono": "^4.0.0",
     "linkedom": "^0.18.12",
     "mime-types": "^3.0.2",

packages/cli/package.json

@@ -32,7 +32,6 @@ var __dirname = __hf_dirname(__filename);`,
     "hono",
     "hono/*",
     "@hono/node-server",
-    "cheerio",
     "mime-types",
     "adm-zip",
     "esbuild",

packages/cli/tsup.config.ts

@@ -109,7 +109,7 @@
     }
   },
   "optionalDependencies": {
-    "cheerio": "^1.2.0",
-    "esbuild": "^0.25.12"
+    "esbuild": "^0.25.12",
+    "linkedom": "^0.18.12"
   }
 }