Add sqlc configuration and core queries

sqlc.yaml (sqlite, schema migrations/, queries migrations/queries/)
generates internal/db with emit_interface. Queries cover dinners (create,
get, list by status, update, archive, set favorite), recipes with
ingredients and steps (upsert by source_url, get, replace children),
photos (insert, get by sha256) and get/upsert for the five settings
singletons. Repository tests run every query against a migrated temp
database.

make sqlc regenerates with the pinned sqlc v1.31.1 (dev tool only, not in
go.mod); make sqlc-check regenerates and fails on any drift in
internal/db, and CI runs it after make test.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

sqlc.yaml

@@ -0,0 +1,15 @@
+# sqlc code generation. Regenerate with `make sqlc` (pinned sqlc version in the
+# Makefile); `make sqlc-check` fails when internal/db is stale. sqlc reads only
+# the top-level *.sql files of the schema directory, so migrations/queries/ is
+# not treated as schema.
+version: "2"
+sql:
+  - engine: sqlite
+    schema: migrations
+    queries: migrations/queries
+    gen:
+      go:
+        package: db
+        out: internal/db
+        sql_package: database/sql
+        emit_interface: true