Split queries.go into focused modules (bd-rgyd)

Split internal/storage/sqlite/queries.go (1586 lines) into logical modules:

- queries.go (650 lines) - Core CRUD: CreateIssue, GetIssue, UpdateIssue, CloseIssue
- queries_search.go (429 lines) - Search/filter: SearchIssues, GetIssueByExternalRef,
  GetCloseReason, GetCloseReasonsForIssues
- queries_delete.go (464 lines) - Delete operations: CreateTombstone, DeleteIssue,
  DeleteIssues and cascade logic
- queries_rename.go (149 lines) - ID/prefix operations: UpdateIssueID,
  RenameDependencyPrefix, RenameCounterPrefix, ResetCounter
- queries_helpers.go (50 lines) - Utilities: parseNullableTimeString,
  parseJSONStringArray, formatJSONStringArray

All tests pass. No functional changes.

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

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

internal/storage/sqlite/queries_helpers.go

@@ -0,0 +1,50 @@
+package sqlite
+
+import (
+	"database/sql"
+	"encoding/json"
+	"time"
+)
+
+// parseNullableTimeString parses a nullable time string from database TEXT columns.
+// The ncruces/go-sqlite3 driver only auto-converts TEXT→time.Time for columns declared
+// as DATETIME/DATE/TIME/TIMESTAMP. For TEXT columns (like deleted_at), we must parse manually.
+// Supports RFC3339, RFC3339Nano, and SQLite's native format.
+func parseNullableTimeString(ns sql.NullString) *time.Time {
+	if !ns.Valid || ns.String == "" {
+		return nil
+	}
+	// Try RFC3339Nano first (more precise), then RFC3339, then SQLite format
+	for _, layout := range []string{time.RFC3339Nano, time.RFC3339, "2006-01-02 15:04:05"} {
+		if t, err := time.Parse(layout, ns.String); err == nil {
+			return &t
+		}
+	}
+	return nil // Unparseable - shouldn't happen with valid data
+}
+
+// parseJSONStringArray parses a JSON string array from database TEXT column.
+// Returns empty slice if the string is empty or invalid JSON.
+func parseJSONStringArray(s string) []string {
+	if s == "" {
+		return nil
+	}
+	var result []string
+	if err := json.Unmarshal([]byte(s), &result); err != nil {
+		return nil // Invalid JSON - shouldn't happen with valid data
+	}
+	return result
+}
+
+// formatJSONStringArray formats a string slice as JSON for database storage.
+// Returns empty string if the slice is nil or empty.
+func formatJSONStringArray(arr []string) string {
+	if len(arr) == 0 {
+		return ""
+	}
+	data, err := json.Marshal(arr)
+	if err != nil {
+		return ""
+	}
+	return string(data)
+}