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>

internal/db/db.go

@@ -0,0 +1,31 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.31.1
+
+package db
+
+import (
+	"context"
+	"database/sql"
+)
+
+type DBTX interface {
+	ExecContext(context.Context, string, ...interface{}) (sql.Result, error)
+	PrepareContext(context.Context, string) (*sql.Stmt, error)
+	QueryContext(context.Context, string, ...interface{}) (*sql.Rows, error)
+	QueryRowContext(context.Context, string, ...interface{}) *sql.Row
+}
+
+func New(db DBTX) *Queries {
+	return &Queries{db: db}
+}
+
+type Queries struct {
+	db DBTX
+}
+
+func (q *Queries) WithTx(tx *sql.Tx) *Queries {
+	return &Queries{
+		db: tx,
+	}
+}