[mangeshraut712]

Summary

This resolves both issues reported in #1193:

1. Exclude fork PRs from child stack discovery (github.ts):
   orderStack previously built the children map from every open pull request (for (const pr of open)), allowing cross-repository (fork) PRs whose base ref matched an upstream branch to be indexed as children. Although byHead excluded fork PRs for downwards resolution, a fork PR targeting an upstream stack branch would still be traversed and pushed to up.

   • Filtered out pr.isCrossRepository when building the children map (if (pr.isCrossRepository) continue;).
   • Added defense-in-depth guard in visit: if (child.isCrossRepository) continue;.
   • Added regression test does not attach a fork PR as a child of a stack branch in github.test.ts.

2. Sanitize terminal blocker output (render.ts):
   Review thread paths, author logins, and comment bodies rendered in blocker summaries could contain ANSI escape sequences (e.g. \x1b[2K, \r, or formatting sequences) and control characters.

   • Introduced sanitizeText to strip ANSI escape sequences (/\\x1b\\[[0-9;]*[a-zA-Z]/g) and C0/C1 control characters (/[\\x00-\\x1f\\x7f-\\x9f]/g).
   • Applied sanitization to path, authorLogin, and bodyLine in threadLine.
   • Sanitized bodyLine before slicing to at most 180 characters.
   • Added regression test sanitizes review thread paths, authors, and comment bodies in blocker output in cli.test.ts.

3. Harness Generation:
   Regenerated harness/pstack/claude-code/ tree via node scripts/generate-pstack-harness-trees.mjs.

Verification

• tsc --project watch-pr/tsconfig.json --noEmit --strict: 0 errors.
• bun test watch-pr: 56/56 passing (160 expectations).
• Full script test suite: 63/63 passing.
• node scripts/generate-pstack-harness-trees.mjs --check: up to date.
• node scripts/validate-plugins.mjs: all plugins validated successfully.
• node scripts/check-pstack-docs.mjs: 0 problems.
• git diff --check: 0 errors.
• Independent code review completed and approved.

Fixes #1193