feat(review): support multi-repo workspace reviews

[Oscar-Silva]

Problem

Plannotator's code review currently requires a git repository as the working directory. For teams working with poly-repo microservices architectures, there's no way to review changes across multiple repos in a single session — each repo needs its own review tab, feedback is fragmented, and the workflow doesn't match how developers actually work (navigating a parent directory with multiple independent services).

Issue #527 captured this gap: users want to run plannotator review from a non-git parent directory and have it automatically discover and review all nested repos with local changes.

Solution

This PR adds multi-repo workspace review — Plannotator can now operate from a non-git parent directory, auto-discover nested git repositories, and present a unified review session covering all repos.

How it works:

1. User runs plannotator review from a non-git parent (e.g., ~/projects/ containing svc-a/, svc-b/, infra/)
2. Plannotator detects all nested git repos with local changes
3. Review UI shows a repo selector — repos with changes are pre-selected
4. Feedback, diff switching, file-content lookups, staging, and agent operations are all repo-aware
5. Workspace-level review feedback covers all repos in one output

Scope:

• Added buildWorkspaceLocalRepos() and buildWorkspacePRRepos() for repo discovery
• Made diff switching, file-content lookups, staging, and agent path routing repo-aware
• Added in-app workspace repo controls (selector, per-repo diffs)
• Full test coverage: workspace discovery, duplicate repo paths, export/file tree/search behavior, non-git root detection
• Backward compatible: single-repo git workflow unchanged

Test plan

• bun test packages/server/review-workspace.test.ts packages/server/vcs.test.ts packages/review-editor/utils/exportFeedback.workspace.test.ts packages/review-editor/utils/buildFileTree.workspace.test.ts packages/review-editor/utils/reviewSearch.workspace.test.ts
• bun run --cwd apps/review build && bun run build:hook && bun run build:opencode
• Manual OpenCode workspace review from a non-git parent directory with multiple nested repos
• Verify repo selector appears in the review UI and repos with local changes are selected by default
• Verify repo-specific diff switching and workspace review feedback work correctly
• Rebased on latest main (May 9, 2026)

Files changed

File	Change
packages/server/review-workspace.ts	New: repo discovery and workspace state management
packages/shared/review-workspace.ts	New: shared workspace types
packages/server/vcs.ts	Add VCS-agnostic repo detection
packages/server/shared-handlers.ts	Wire workspace repos into review server
packages/server/claude-review.ts	Repo-aware agent prompts
packages/server/codex-review.ts	Repo-aware agent prompts
apps/hook/server/index.ts	Hook entry: workspace vs single-repo branching
Plus 5 test files	Regression coverage for workspace discovery, export, file tree, search, and agent jobs

Closes #527

[Oscar-Silva]

👋 @backnotprop — this PR has been rebased on latest main and is ready for review. It implements the multi-repo workspace review feature requested in #527.

TL;DR: Lets plannotator review discover and review all nested repos with local changes from a non-git parent directory — ideal for poly-repo microservices setups where devs work across multiple services at once.

All tests pass and the build is clean. Would love your eyes on this when you have a moment!