Add the dinners API for Regulars

POST /api/v1/dinners adds a Regular from a name or a recipe link
(status and origin regular, grounding_status pending), refusing a name
harness.Similar to an unarchived dinner, or a known link, with 409.
GET /dinners?status=regular|quest_log lists dinners with photo URLs and
grounding status; PATCH /dinners/{id} edits name, method, minutes and
difficulty; DELETE archives the row; POST /dinners/{id}/favorite toggles
is_favorite. Every write records the session subject as updated_by.

Migration 0008 adds dinners.recipe_url so a pasted link is kept until
grounding resolves it.

Maestro task 28d3cb4b-83d1-40e8-991f-d88f0f64d270.

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

internal/db/models.go

@@ -67,6 +67,7 @@ type Dinner struct {
 	UpdatedBy       sql.NullString
 	CreatedAt       string
 	UpdatedAt       string
+	RecipeUrl       sql.NullString
 }
 
 type HouseholdSetting struct {