Phase 2 sub-commit 1: Doctrine ORM 3 + Migrations + SQLite

Skeleton gains Doctrine ORM 3.6 (with DoctrineBundle 3.x and Migrations
4.x), pointed at a SQLite file under var/data.sqlite. Apps move to
Postgres/MySQL by overriding DATABASE_URL in .env.local.

config/packages/doctrine.yaml registers the symfony/uid UuidType so
Phase 2 sub-commit 4's UUIDv7 default works without per-app config,
and pre-wires the App\Entity attribute mapping under src/Entity/ for
the maker to drop entities into.

Bundle gains an optional doctrine/dbal Connection via Autowire; when
present, bridge:doctor adds a "Database reachable" SELECT-1 probe.
The bundle still installs cleanly without doctrine/dbal — apps that
opt out get a doctor table without the database row.

Verified: `bin/console bridge:doctor` is all green against a fresh
SQLite. composer quality (PHPStan + cs-fixer + PHPUnit) stays green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

framework/skeleton/symfony/config/bundles.php

@@ -4,5 +4,7 @@ return [
     Symfony\Bundle\FrameworkBundle\FrameworkBundle::class => ['all' => true],
     Symfony\Bundle\SecurityBundle\SecurityBundle::class => ['all' => true],
     Symfony\Bundle\MercureBundle\MercureBundle::class => ['all' => true],
+    Doctrine\Bundle\DoctrineBundle\DoctrineBundle::class => ['all' => true],
+    Doctrine\Bundle\MigrationsBundle\DoctrineMigrationsBundle::class => ['all' => true],
     PhpQml\Bridge\BridgeBundle::class => ['all' => true],
 ];

framework/skeleton/symfony/config/packages/doctrine.yaml

@@ -0,0 +1,38 @@
+doctrine:
+    dbal:
+        url: '%env(resolve:DATABASE_URL)%'
+        # SQLite default for dev — see .env.
+        # Apps swap this to Postgres / MySQL when they outgrow it.
+        types:
+            uuid: Symfony\Bridge\Doctrine\Types\UuidType
+    orm:
+        validate_xml_mapping: true
+        naming_strategy: doctrine.orm.naming_strategy.underscore_number_aware
+        identity_generation_preferences:
+            Doctrine\DBAL\Platforms\PostgreSQLPlatform: identity
+        auto_mapping: true
+        mappings:
+            App:
+                type: attribute
+                is_bundle: false
+                dir: '%kernel.project_dir%/src/Entity'
+                prefix: 'App\Entity'
+                alias: App
+
+when@prod:
+    doctrine:
+        orm:
+            query_cache_driver:
+                type: pool
+                pool: doctrine.system_cache_pool
+            result_cache_driver:
+                type: pool
+                pool: doctrine.result_cache_pool
+
+    framework:
+        cache:
+            pools:
+                doctrine.result_cache_pool:
+                    adapter: cache.app
+                doctrine.system_cache_pool:
+                    adapter: cache.system

framework/skeleton/symfony/config/packages/doctrine_migrations.yaml

@@ -0,0 +1,4 @@
+doctrine_migrations:
+    migrations_paths:
+        'DoctrineMigrations': '%kernel.project_dir%/migrations'
+    enable_profiler: false