feat: Add bd init --contributor and --team wizards

- Implement OSS contributor workflow wizard
  - Auto-detects fork relationships (upstream remote)
  - Checks push access (SSH vs HTTPS)
  - Creates separate planning repository
  - Configures auto-routing to keep planning out of PRs

- Implement team workflow wizard
  - Detects protected main branches
  - Creates sync branch if needed
  - Configures auto-commit/auto-push
  - Supports both direct and PR-based workflows

- Add comprehensive documentation
  - examples/contributor-workflow/README.md
  - examples/team-workflow/README.md
  - Updated AGENTS.md, README.md, QUICKSTART.md
  - Updated docs/MULTI_REPO_MIGRATION.md

Closes: bd-kla1, bd-twlr, bd-6z7l
Amp-Thread-ID: https://ampcode.com/threads/T-b4d124a2-447e-47d1-8124-d7c5dab9a97b
Co-authored-by: Amp <amp@ampcode.com>

QUICKSTART.md

@@ -10,6 +10,30 @@ go build -o bd ./cmd/bd
 ./bd --help
 ```
 
+## Initialize
+
+First time in a repository:
+
+```bash
+# Basic setup
+bd init
+
+# OSS contributor (fork workflow with separate planning repo)
+bd init --contributor
+
+# Team member (branch workflow for collaboration)
+bd init --team
+
+# Protected main branch (GitHub/GitLab)
+bd init --branch beads-metadata
+```
+
+The wizard will:
+- Create `.beads/` directory and database
+- Import existing issues from git (if any)
+- Prompt to install git hooks (recommended)
+- Auto-start daemon for sync
+
 ## Your First Issues
 
 ```bash