Refactor: consolidate ID generation and shared helpers (bd-0702, bd-1445)

- Created ids.go with ValidateIssueIDPrefix, GenerateIssueID, EnsureIDs
- Created issues.go with insertIssue/insertIssues helpers
- Created events_helpers.go with recordCreatedEvent/recordCreatedEvents
- Created dirty_helpers.go with markDirty/markDirtyBatch
- Refactored sqlite.go and batch_ops.go to use new helpers
- Removed duplicate code from hash_ids.go

Amp-Thread-ID: https://ampcode.com/threads/T-b1ab5a16-96de-4e4d-b255-3617055a89eb
Co-authored-by: Amp <amp@ampcode.com>

internal/storage/sqlite/events_helpers.go

@@ -0,0 +1,55 @@
+package sqlite
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"fmt"
+
+	"github.com/steveyegge/beads/internal/types"
+)
+
+// recordCreatedEvent records a single creation event for an issue
+func recordCreatedEvent(ctx context.Context, conn *sql.Conn, issue *types.Issue, actor string) error {
+	eventData, err := json.Marshal(issue)
+	if err != nil {
+		// Fall back to minimal description if marshaling fails
+		eventData = []byte(fmt.Sprintf(`{"id":"%s","title":"%s"}`, issue.ID, issue.Title))
+	}
+	eventDataStr := string(eventData)
+	
+	_, err = conn.ExecContext(ctx, `
+		INSERT INTO events (issue_id, event_type, actor, new_value)
+		VALUES (?, ?, ?, ?)
+	`, issue.ID, types.EventCreated, actor, eventDataStr)
+	if err != nil {
+		return fmt.Errorf("failed to record event: %w", err)
+	}
+	return nil
+}
+
+// recordCreatedEvents bulk records creation events for multiple issues
+func recordCreatedEvents(ctx context.Context, conn *sql.Conn, issues []*types.Issue, actor string) error {
+	stmt, err := conn.PrepareContext(ctx, `
+		INSERT INTO events (issue_id, event_type, actor, new_value)
+		VALUES (?, ?, ?, ?)
+	`)
+	if err != nil {
+		return fmt.Errorf("failed to prepare event statement: %w", err)
+	}
+	defer func() { _ = stmt.Close() }()
+
+	for _, issue := range issues {
+		eventData, err := json.Marshal(issue)
+		if err != nil {
+			// Fall back to minimal description if marshaling fails
+			eventData = []byte(fmt.Sprintf(`{"id":"%s","title":"%s"}`, issue.ID, issue.Title))
+		}
+
+		_, err = stmt.ExecContext(ctx, issue.ID, types.EventCreated, actor, string(eventData))
+		if err != nil {
+			return fmt.Errorf("failed to record event for %s: %w", issue.ID, err)
+		}
+	}
+	return nil
+}