chore: remove issue ID references from comments and changelogs

Strip (bd-xxx), (gt-xxx) suffixes from code comments and changelog
entries. The descriptions remain meaningful without the ephemeral
issue IDs.

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

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

internal/storage/sqlite/migrations/015_blocked_issues_cache.go

@@ -7,7 +7,7 @@ import (
 
 // MigrateBlockedIssuesCache creates the blocked_issues_cache table for performance optimization
 // This cache materializes the recursive CTE computation from GetReadyWork to avoid
-// expensive recursive queries on every call (bd-5qim)
+// expensive recursive queries on every call
 func MigrateBlockedIssuesCache(db *sql.DB) error {
 	// Check if table already exists
 	var tableName string