feat(close): Add --suggest-next flag to show newly unblocked issues (GH#679)

When closing an issue, the new --suggest-next flag returns a list of
issues that became unblocked (ready to work on) as a result of the close.

This helps agents and users quickly identify what work is now available
after completing a blocker.

Example:
  $ bd close bd-5 --suggest-next
  ✓ Closed bd-5: Completed

  Newly unblocked:
    • bd-7 "Implement feature X" (P1)
    • bd-8 "Write tests for X" (P2)

Implementation:
- Added GetNewlyUnblockedByClose to storage interface
- Implemented efficient single-query for SQLite using blocked_issues_cache
- Added SuggestNext field to CloseArgs in RPC protocol
- Added CloseResult type for structured response
- CLI handles both daemon and direct modes

Thanks to @kraitsura for the detailed feature request and design.

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.beads/issues.jsonl

@@ -450,7 +450,7 @@
 {"id":"bd-qqc.7","title":"Push release v{{version}} to remote","description":"Push the commit and tag:\n\n```bash\ngit push \u0026\u0026 git push --tags\n```\n\nVerify on GitHub that the tag appears in releases.","status":"tombstone","priority":1,"issue_type":"task","created_at":"2025-12-18T13:00:26.933082-08:00","updated_at":"2025-12-24T16:25:30.689807-08:00","dependencies":[{"issue_id":"bd-qqc.7","depends_on_id":"bd-qqc","type":"parent-child","created_at":"2025-12-18T13:00:26.933687-08:00","created_by":"stevey"},{"issue_id":"bd-qqc.7","depends_on_id":"bd-qqc.6","type":"blocks","created_at":"2025-12-18T13:01:12.711161-08:00","created_by":"stevey"}],"deleted_at":"2025-12-24T16:25:30.689807-08:00","deleted_by":"daemon","delete_reason":"delete","original_type":"task"}
 {"id":"bd-qqc.8","title":"Create and push git tag v{{version}}","description":"Create the release tag and push it:\n\n```bash\ngit tag v{{version}}\ngit push origin v{{version}}\n```\n\nThis triggers the GoReleaser GitHub Action to build release binaries.","status":"tombstone","priority":1,"issue_type":"task","created_at":"2025-12-18T22:42:34.659927-08:00","updated_at":"2025-12-24T16:25:30.608841-08:00","dependencies":[{"issue_id":"bd-qqc.8","depends_on_id":"bd-qqc","type":"parent-child","created_at":"2025-12-18T22:42:34.660248-08:00","created_by":"daemon"},{"issue_id":"bd-qqc.8","depends_on_id":"bd-vgi5","type":"blocks","created_at":"2025-12-18T22:43:21.209529-08:00","created_by":"daemon"}],"deleted_at":"2025-12-24T16:25:30.608841-08:00","deleted_by":"daemon","delete_reason":"delete","original_type":"task"}
 {"id":"bd-qqc.9","title":"Update Homebrew formula","description":"Update the Homebrew tap with new version:\n\n```bash\n./scripts/update-homebrew.sh {{version}}\n```\n\nThis script waits for GitHub Actions to complete (~5 min), then updates the formula with new SHA256 hashes.\n\nAfter running, verify the formula with:\n\n```bash\nbrew info steveyegge/beads/bd\n```","status":"tombstone","priority":1,"issue_type":"task","created_at":"2025-12-18T22:42:35.815096-08:00","updated_at":"2025-12-24T16:25:30.525596-08:00","dependencies":[{"issue_id":"bd-qqc.9","depends_on_id":"bd-qqc","type":"parent-child","created_at":"2025-12-18T22:42:35.816752-08:00","created_by":"daemon"},{"issue_id":"bd-qqc.9","depends_on_id":"bd-qqc.8","type":"blocks","created_at":"2025-12-18T22:43:21.332955-08:00","created_by":"daemon"}],"deleted_at":"2025-12-24T16:25:30.525596-08:00","deleted_by":"daemon","delete_reason":"delete","original_type":"task"}
-{"id":"bd-qy37","title":"Work on gt-8tmz.36: Validate expanded step IDs are unique...","description":"Work on gt-8tmz.36: Validate expanded step IDs are unique. After ApplyExpansions in internal/formula/expand.go, new steps can be created that might have duplicate IDs. Add validation in ApplyExpansions to check for duplicate step IDs after expansion. If duplicates found, return an error with the duplicate IDs. Add test in expand_test.go. When done, commit and push to main.","status":"in_progress","priority":2,"issue_type":"task","assignee":"beads/slit","created_at":"2025-12-25T20:01:27.048018-08:00","updated_at":"2025-12-25T20:01:27.135376-08:00"}
+{"id":"bd-qy37","title":"Work on gt-8tmz.36: Validate expanded step IDs are unique...","description":"Work on gt-8tmz.36: Validate expanded step IDs are unique. After ApplyExpansions in internal/formula/expand.go, new steps can be created that might have duplicate IDs. Add validation in ApplyExpansions to check for duplicate step IDs after expansion. If duplicates found, return an error with the duplicate IDs. Add test in expand_test.go. When done, commit and push to main.","status":"closed","priority":2,"issue_type":"task","assignee":"beads/slit","created_at":"2025-12-25T20:01:27.048018-08:00","updated_at":"2025-12-25T20:04:42.594254-08:00","closed_at":"2025-12-25T20:04:42.594254-08:00","close_reason":"Implemented step ID validation in ApplyExpansions with tests"}
 {"id":"bd-r06v","title":"Merge: bd-phtv","description":"branch: polecat/Pinner\ntarget: main\nsource_issue: bd-phtv\nrig: beads","status":"closed","priority":1,"issue_type":"merge-request","created_at":"2025-12-23T13:48:16.853715-08:00","updated_at":"2025-12-23T19:12:08.342414-08:00","closed_at":"2025-12-23T19:12:08.342414-08:00","close_reason":"Stale merge-requests from orphaned polecat branches - refinery not processing"}
 {"id":"bd-r2n1","title":"Add integration tests for RPC server and event loops","description":"After adding basic unit tests for daemon utilities, the complex daemon functions still need integration tests:\n\nCore daemon lifecycle:\n- startRPCServer: Initializes and starts RPC server with proper error handling\n- runEventLoop: Polling-based sync loop with parent monitoring and signal handling\n- runDaemonLoop: Main daemon initialization and setup\n\nHealth checking:\n- isDaemonHealthy: Checks daemon responsiveness and health metrics\n- checkDaemonHealth: Periodic health verification\n\nThese require more complex test infrastructure (mock RPC, test contexts, signal handling) and should be tackled after the unit test foundation is in place.","status":"closed","priority":1,"issue_type":"task","created_at":"2025-12-18T12:28:56.022996362-07:00","updated_at":"2025-12-18T12:44:32.167862713-07:00","closed_at":"2025-12-18T12:44:32.167862713-07:00","dependencies":[{"issue_id":"bd-r2n1","depends_on_id":"bd-4or","type":"discovered-from","created_at":"2025-12-18T12:28:56.045893852-07:00","created_by":"mhwilkie"}]}
 {"id":"bd-r36u","title":"gt mq list shows empty when MRs exist","status":"closed","priority":2,"issue_type":"bug","created_at":"2025-12-20T01:13:07.561256-08:00","updated_at":"2025-12-21T17:51:25.891037-08:00","closed_at":"2025-12-21T17:51:25.891037-08:00","close_reason":"Moved to gastown: gt-uhc3"}