feat: campos documentation, notes y code en registry

Añade campos documentation, notes y code a functions y types.
El parser extrae el contenido del .md y el código fuente del archivo
referenciado en file_path. El indexer los almacena en SQLite y los
incluye en FTS5 para búsqueda sobre código y documentación.
Nueva migración 003_documentation.sql para añadir las columnas.

registry/migrations/003_documentation.sql

@@ -0,0 +1,103 @@
+-- Add documentation fields to functions and types.
+-- examples: extracted code blocks from ## Ejemplo
+-- notes: extracted text from ## Notas
+-- documentation: remaining body text from .md
+-- code: source code from the referenced .go/.py/.tsx file
+
+ALTER TABLE functions ADD COLUMN notes         TEXT NOT NULL DEFAULT '';
+ALTER TABLE functions ADD COLUMN documentation  TEXT NOT NULL DEFAULT '';
+ALTER TABLE functions ADD COLUMN code           TEXT NOT NULL DEFAULT '';
+
+ALTER TABLE types ADD COLUMN examples      TEXT NOT NULL DEFAULT '';
+ALTER TABLE types ADD COLUMN notes         TEXT NOT NULL DEFAULT '';
+ALTER TABLE types ADD COLUMN documentation TEXT NOT NULL DEFAULT '';
+ALTER TABLE types ADD COLUMN code          TEXT NOT NULL DEFAULT '';
+
+-- Rebuild FTS for functions: add examples, notes, documentation, code
+DROP TRIGGER IF EXISTS functions_ai;
+DROP TRIGGER IF EXISTS functions_ad;
+DROP TRIGGER IF EXISTS functions_au;
+
+INSERT INTO functions_fts(functions_fts) VALUES('rebuild');
+DROP TABLE IF EXISTS functions_fts;
+
+CREATE VIRTUAL TABLE functions_fts USING fts5(
+    id,
+    name,
+    description,
+    tags,
+    signature,
+    domain,
+    example,
+    notes,
+    documentation,
+    code,
+    content='functions',
+    content_rowid='rowid'
+);
+
+-- Populate FTS from existing data
+INSERT INTO functions_fts(rowid, id, name, description, tags, signature, domain, example, notes, documentation, code)
+SELECT rowid, id, name, description, tags, signature, domain, example, notes, documentation, code
+FROM functions;
+
+CREATE TRIGGER functions_ai AFTER INSERT ON functions BEGIN
+    INSERT INTO functions_fts(rowid, id, name, description, tags, signature, domain, example, notes, documentation, code)
+    VALUES (new.rowid, new.id, new.name, new.description, new.tags, new.signature, new.domain, new.example, new.notes, new.documentation, new.code);
+END;
+
+CREATE TRIGGER functions_ad AFTER DELETE ON functions BEGIN
+    INSERT INTO functions_fts(functions_fts, rowid, id, name, description, tags, signature, domain, example, notes, documentation, code)
+    VALUES ('delete', old.rowid, old.id, old.name, old.description, old.tags, old.signature, old.domain, old.example, old.notes, old.documentation, old.code);
+END;
+
+CREATE TRIGGER functions_au AFTER UPDATE ON functions BEGIN
+    INSERT INTO functions_fts(functions_fts, rowid, id, name, description, tags, signature, domain, example, notes, documentation, code)
+    VALUES ('delete', old.rowid, old.id, old.name, old.description, old.tags, old.signature, old.domain, old.example, old.notes, old.documentation, old.code);
+    INSERT INTO functions_fts(rowid, id, name, description, tags, signature, domain, example, notes, documentation, code)
+    VALUES (new.rowid, new.id, new.name, new.description, new.tags, new.signature, new.domain, new.example, new.notes, new.documentation, new.code);
+END;
+
+-- Rebuild FTS for types: add examples, notes, documentation, code
+DROP TRIGGER IF EXISTS types_ai;
+DROP TRIGGER IF EXISTS types_ad;
+DROP TRIGGER IF EXISTS types_au;
+
+INSERT INTO types_fts(types_fts) VALUES('rebuild');
+DROP TABLE IF EXISTS types_fts;
+
+CREATE VIRTUAL TABLE types_fts USING fts5(
+    id,
+    name,
+    description,
+    tags,
+    domain,
+    examples,
+    notes,
+    documentation,
+    code,
+    content='types',
+    content_rowid='rowid'
+);
+
+-- Populate FTS from existing data
+INSERT INTO types_fts(rowid, id, name, description, tags, domain, examples, notes, documentation, code)
+SELECT rowid, id, name, description, tags, domain, examples, notes, documentation, code
+FROM types;
+
+CREATE TRIGGER types_ai AFTER INSERT ON types BEGIN
+    INSERT INTO types_fts(rowid, id, name, description, tags, domain, examples, notes, documentation, code)
+    VALUES (new.rowid, new.id, new.name, new.description, new.tags, new.domain, new.examples, new.notes, new.documentation, new.code);
+END;
+
+CREATE TRIGGER types_ad AFTER DELETE ON types BEGIN
+    INSERT INTO types_fts(types_fts, rowid, id, name, description, tags, domain, examples, notes, documentation, code)
+    VALUES ('delete', old.rowid, old.id, old.name, old.description, old.tags, old.domain, old.examples, old.notes, old.documentation, old.code);
+END;
+
+CREATE TRIGGER types_au AFTER UPDATE ON types BEGIN
+    INSERT INTO types_fts(types_fts, rowid, id, name, description, tags, domain, examples, notes, documentation, code)
+    VALUES ('delete', old.rowid, old.id, old.name, old.description, old.tags, old.domain, old.examples, old.notes, old.documentation, old.code);
+    INSERT INTO types_fts(rowid, id, name, description, tags, domain, examples, notes, documentation, code)
+    VALUES (new.rowid, new.id, new.name, new.description, new.tags, new.domain, new.examples, new.notes, new.documentation, new.code);
+END;