Fix Feature 12 review findings F2–F8 on Regular grounding and onboarding

Grounding (F2–F5):
- Each ground_dinner job carries the dinner's new grounding_revision
  (migration 0010). Renaming a pending Regular raises the revision, and a
  job only grounds and writes a dinner still at its revision, so a queued
  original job no longer grounds the new name or decides the outcome.
- Background grounding keeps a method, minutes or difficulty a member saved
  while the Regular was pending, and fills only those left empty.
- Grounding by hand clears the pasted recipe_url, and link deduplication
  uses the source_url of the attached recipe, else the pending link.
- Archived dinners are not grounded: the job checks before any search,
  fetch or model call, and its final update requires an unarchived row.

Onboarding (F6, F7):
- Step 3 shows "Add Regulars" back to step 2 when the server refuses to
  finish with fewer than three Regulars.
- Common picks are hidden by a copy of harness Normalize/Similar, checked
  against the same shared cases as the Go code.

Docs (F8): ARCHITECTURE.md covers the three-Regular minimum, step-3
recovery, the grounding revision and the dedupe rules.

F1 was fixed in 1304487; its test now also asserts the old link is never
grounded and recipe_url stays cleared.

Maestro task 5037ff86-181d-448e-927b-c2fd2258a25d.

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

internal/db/querier.go

@@ -36,14 +36,15 @@ type Querier interface {
 	DeleteRecipeIngredients(ctx context.Context, recipeID string) error
 	DeleteRecipeSteps(ctx context.Context, recipeID string) error
 	FailJob(ctx context.Context, arg FailJobParams) (int64, error)
-	// Fails every dinner still pending whose grounding job is no longer queued
-	// or running: the process stopped before the job, or before its handler
-	// recorded a result. Run at boot, after the job runner fails the jobs a
-	// previous process left running.
+	// Fails every dinner still pending whose grounding job for its current
+	// grounding_revision is no longer queued or running: the process stopped
+	// before the job, or before its handler recorded a result. Run at boot,
+	// after the job runner fails the jobs a previous process left running.
 	FailOrphanedPendingDinnerGroundings(ctx context.Context, arg FailOrphanedPendingDinnerGroundingsParams) (int64, error)
-	// Records why the background grounding of a dinner still pending under the
-	// normalized name it was grounded for failed; a dinner grounded some other
-	// way or renamed meanwhile is left as it is (0 rows).
+	// Records why the background grounding of an unarchived dinner still
+	// pending at the grounding_revision it was grounded for failed; a dinner
+	// grounded some other way, renamed or archived meanwhile is left as it is
+	// (0 rows).
 	FailPendingDinnerGrounding(ctx context.Context, arg FailPendingDinnerGroundingParams) (int64, error)
 	// Fails every job left running, at boot before any worker starts.
 	FailRunningJobs(ctx context.Context, arg FailRunningJobsParams) (int64, error)
@@ -65,12 +66,15 @@ type Querier interface {
 	GetRecipeBySourceURL(ctx context.Context, sourceUrl string) (Recipe, error)
 	// Returns sql.ErrNoRows until the row exists.
 	GetRecipeSearchSettings(ctx context.Context) (RecipeSearchSetting, error)
-	// Records a dinner's grounding (grounded or manual) and clears any
-	// grounding_error. An unknown id returns sql.ErrNoRows.
+	// Records a dinner's grounding by hand (grounded or manual) and clears any
+	// grounding_error and pasted recipe_url: the recipe chosen replaces the
+	// link. An unknown id returns sql.ErrNoRows.
 	GroundDinner(ctx context.Context, arg GroundDinnerParams) (Dinner, error)
-	// Records the background grounding of a dinner still pending under the
-	// normalized name it was grounded for; a dinner grounded some other way or
-	// renamed meanwhile is left as it is (0 rows).
+	// Records the background grounding of an unarchived dinner still pending at
+	// the grounding_revision it was grounded for; a dinner grounded some other
+	// way, renamed or archived meanwhile is left as it is (0 rows). A method,
+	// minutes_total or difficulty already set is kept: a pending dinner has
+	// them only when a member edited them while it was grounding.
 	GroundPendingDinner(ctx context.Context, arg GroundPendingDinnerParams) (int64, error)
 	ListDinnersByStatus(ctx context.Context, status string) ([]Dinner, error)
 	// The planned dinners dated from from_date up to but not including
@@ -81,8 +85,9 @@ type Querier interface {
 	ListRecentDeclinedNames(ctx context.Context, limit int64) ([]string, error)
 	ListRecipeIngredients(ctx context.Context, recipeID string) ([]RecipeIngredient, error)
 	ListRecipeSteps(ctx context.Context, recipeID string) ([]RecipeStep, error)
-	// Every dinner a new or renamed dinner must not repeat.
-	ListUnarchivedDinners(ctx context.Context) ([]Dinner, error)
+	// Every dinner a new or renamed dinner must not repeat, with the
+	// source_url of the recipe it is grounded in (NULL while it has none).
+	ListUnarchivedDinners(ctx context.Context) ([]ListUnarchivedDinnersRow, error)
 	// Stores a partial result of a running job.
 	PublishJobResult(ctx context.Context, arg PublishJobResultParams) (int64, error)
 	// An unknown id returns sql.ErrNoRows.