feat: tabla apps en registry — modelo, parser, indexer y CLI

Agrega soporte completo para indexar aplicaciones del directorio apps/.
Cada app tiene un descriptor app.md con frontmatter YAML que el indexer
recoge automaticamente. Incluye migracion 004, modelo App, ParseAppMD,
ValidateApp, store CRUD con FTS5, y soporte en fn list/search/show.
Crea descriptores app.md para docker_tui, pipeline_launcher y metabase_registry.

registry/store.go

@@ -261,12 +261,118 @@ func (db *DB) DeleteType(id string) error {
 	return err
 }
 
-// Purge deletes all data from both tables. Used before re-indexing.
+// InsertApp inserts or replaces an app entry.
+func (db *DB) InsertApp(a *App) error {
+	now := time.Now().UTC().Format(time.RFC3339)
+	if a.CreatedAt.IsZero() {
+		a.CreatedAt = time.Now().UTC()
+	}
+	a.UpdatedAt = time.Now().UTC()
+
+	if a.ID == "" {
+		a.ID = GenerateID(a.Name, a.Lang, a.Domain)
+	}
+
+	_, err := db.conn.Exec(`
+		INSERT OR REPLACE INTO apps (
+			id, name, lang, domain, description, tags,
+			uses_functions, uses_types, framework, entry_point,
+			documentation, notes, dir_path, created_at, updated_at
+		) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
+		a.ID, a.Name, a.Lang, a.Domain, a.Description, marshalStrings(a.Tags),
+		marshalStrings(a.UsesFunctions), marshalStrings(a.UsesTypes), a.Framework, a.EntryPoint,
+		a.Documentation, a.Notes, a.DirPath, a.CreatedAt.Format(time.RFC3339), now,
+	)
+	return err
+}
+
+// GetApp returns a single app by ID.
+func (db *DB) GetApp(id string) (*App, error) {
+	rows, err := db.conn.Query("SELECT * FROM apps WHERE id = ?", id)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	apps, err := scanApps(rows)
+	if err != nil {
+		return nil, err
+	}
+	if len(apps) == 0 {
+		return nil, fmt.Errorf("app %q not found", id)
+	}
+	return &apps[0], nil
+}
+
+// SearchApps performs FTS search on apps with optional filters.
+func (db *DB) SearchApps(query string, lang, domain string) ([]App, error) {
+	where := []string{}
+	args := []any{}
+
+	if query != "" {
+		where = append(where, "a.id IN (SELECT id FROM apps_fts WHERE apps_fts MATCH ?)")
+		args = append(args, query)
+	}
+	if lang != "" {
+		where = append(where, "a.lang = ?")
+		args = append(args, lang)
+	}
+	if domain != "" {
+		where = append(where, "a.domain = ?")
+		args = append(args, domain)
+	}
+
+	sql := "SELECT * FROM apps a"
+	if len(where) > 0 {
+		sql += " WHERE " + strings.Join(where, " AND ")
+	}
+	sql += " ORDER BY a.name"
+
+	rows, err := db.conn.Query(sql, args...)
+	if err != nil {
+		return nil, fmt.Errorf("search apps: %w", err)
+	}
+	defer rows.Close()
+
+	return scanApps(rows)
+}
+
+func scanApps(rows interface{ Next() bool; Scan(...any) error }) ([]App, error) {
+	var result []App
+	for rows.Next() {
+		var a App
+		var tagsJSON, usesFnJSON, usesTypJSON string
+		var createdAt, updatedAt string
+
+		err := rows.Scan(
+			&a.ID, &a.Name, &a.Lang, &a.Domain, &a.Description, &tagsJSON,
+			&usesFnJSON, &usesTypJSON, &a.Framework, &a.EntryPoint,
+			&a.Documentation, &a.Notes, &a.DirPath, &createdAt, &updatedAt,
+		)
+		if err != nil {
+			return nil, fmt.Errorf("scanning app: %w", err)
+		}
+
+		a.Tags = unmarshalStrings(tagsJSON)
+		a.UsesFunctions = unmarshalStrings(usesFnJSON)
+		a.UsesTypes = unmarshalStrings(usesTypJSON)
+		a.CreatedAt, _ = time.Parse(time.RFC3339, createdAt)
+		a.UpdatedAt, _ = time.Parse(time.RFC3339, updatedAt)
+
+		result = append(result, a)
+	}
+	return result, nil
+}
+
+// Purge deletes all data from functions, types and apps. Used before re-indexing.
 func (db *DB) Purge() error {
 	if _, err := db.conn.Exec("DELETE FROM functions"); err != nil {
 		return err
 	}
-	_, err := db.conn.Exec("DELETE FROM types")
+	if _, err := db.conn.Exec("DELETE FROM types"); err != nil {
+		return err
+	}
+	_, err := db.conn.Exec("DELETE FROM apps")
 	return err
 }