fix(storage): add reconnectMu RLock protection to prevent race condition (#1054)

Add missing reconnectMu.RLock() protection to storage methods that were
vulnerable to the same race condition fixed in GH#607. The FreshnessChecker
can trigger reconnect() which closes s.db while queries are in flight,
causing "database is closed" errors during daemon export operations.

Protected methods:
- labels.go: GetLabelsForIssues (GetLabels intentionally unprotected - called from GetIssue which holds lock)
- comments.go: GetIssueComments, GetCommentsForIssues
- dependencies.go: GetDependencyCounts, GetDependencyRecords, GetAllDependencyRecords, GetDependencyTree, loadDependencyGraph
- config.go: SetConfig, GetConfig, GetAllConfig, DeleteConfig, SetMetadata, GetMetadata
- dirty.go: MarkIssueDirty, GetDirtyIssues, GetDirtyIssueHash, GetDirtyIssueCount
- events.go: GetEvents, GetStatistics, GetMoleculeProgress
- hash.go: All hash methods
- hash_ids.go: GetNextChildID, ensureChildCounterUpdated (getNextChildNumber unprotected - called internally)

Internal helpers called from already-locked contexts intentionally omit
RLock to avoid deadlock (Go's RWMutex doesn't support recursive locking).

Fixes: bd-vx7fp

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

Executed-By: beads/crew/dave
Rig: beads
Role: crew

internal/storage/sqlite/comments.go

@@ -102,6 +102,11 @@ func (s *SQLiteStorage) ImportIssueComment(ctx context.Context, issueID, author,
 
 // GetIssueComments retrieves all comments for an issue
 func (s *SQLiteStorage) GetIssueComments(ctx context.Context, issueID string) ([]*types.Comment, error) {
+	// Hold read lock during database operations to prevent reconnect() from
+	// closing the connection mid-query (GH#607 race condition fix)
+	s.reconnectMu.RLock()
+	defer s.reconnectMu.RUnlock()
+
 	rows, err := s.db.QueryContext(ctx, `
 		SELECT id, issue_id, author, text, created_at
 		FROM comments
@@ -137,6 +142,11 @@ func (s *SQLiteStorage) GetCommentsForIssues(ctx context.Context, issueIDs []str
 		return make(map[string][]*types.Comment), nil
 	}
 
+	// Hold read lock during database operations to prevent reconnect() from
+	// closing the connection mid-query (GH#607 race condition fix)
+	s.reconnectMu.RLock()
+	defer s.reconnectMu.RUnlock()
+
 	// Build placeholders for IN clause
 	placeholders := make([]interface{}, len(issueIDs))
 	for i, id := range issueIDs {