feat: persistent storage for Deno static sites

- Add storage_enabled and storage_limit_mb columns to static_sites.
- Create/attach Docker volumes (tinyforge-site-{name}-data) for Deno
  sites with storage enabled, mounted at /app/data.
- Grant --allow-write=/app/data in Deno container CMD.
- Add storage usage API endpoint (GET /api/sites/{id}/storage).
- Show storage section in site detail page with usage bar.
- Add storage toggle and limit field to new site wizard.
- Use ConfirmDialog for secret deletion instead of inline delete.

internal/store/store.go

@@ -125,6 +125,9 @@ func (s *Store) runMigrations() error {
 		`ALTER TABLE settings ADD COLUMN image_prune_threshold_mb INTEGER NOT NULL DEFAULT 1024`,
 		// Add provider column to static_sites (2026-04-11).
 		`ALTER TABLE static_sites ADD COLUMN provider TEXT NOT NULL DEFAULT ''`,
+		// Add persistent storage columns to static_sites (2026-04-12).
+		`ALTER TABLE static_sites ADD COLUMN storage_enabled INTEGER NOT NULL DEFAULT 0`,
+		`ALTER TABLE static_sites ADD COLUMN storage_limit_mb INTEGER NOT NULL DEFAULT 0`,
 	}
 
 	for _, m := range migrations {