Add plan service and weekly plan API

Add internal/plan: a draft_week job that drafts the week through the
harness from every Regular and the Quest log dinners no other current or
later plan holds, given the household context and last week's dinners,
and stores it as the week's plan; plan reads with the week label, is_new
and each crock-pot dinner's start_by (dinner time minus minutes_total,
computed on read); and day swaps that recompute is_new and move a synced
plan to changed. Drafting over a synced or changed plan needs confirm, at
enqueue and again when the job stores the week; a redraft keeps each
day's calendar event id.

Serve GET /api/v1/plans/{weekStart}, POST /api/v1/plans/{weekStart}/draft
(202 {job_id}, single-flight per week) and PUT
/api/v1/plans/{weekStart}/days/{date}; a weekStart that is not a Monday
is 400 invalid_week.

Maestro task ea48e650-d510-49cc-8485-0f07174ee731.

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

internal/db/querier.go

@@ -38,6 +38,7 @@ type Querier interface {
 	// later renamed.
 	CreateSuggestion(ctx context.Context, arg CreateSuggestionParams) error
 	CreateSuggestionBatch(ctx context.Context, arg CreateSuggestionBatchParams) (SuggestionBatch, error)
+	CreateWeekPlan(ctx context.Context, arg CreateWeekPlanParams) error
 	// Records the household's decision on a pending suggestion; one already
 	// decided is left as it is (0 rows).
 	DecideSuggestion(ctx context.Context, arg DecideSuggestionParams) (int64, error)
@@ -67,6 +68,9 @@ type Querier interface {
 	FinishSuggestionBatch(ctx context.Context, arg FinishSuggestionBatchParams) (int64, error)
 	// Returns sql.ErrNoRows until the row exists.
 	GetAISettings(ctx context.Context) (AiSetting, error)
+	// The id of the job of kind queued or running for the week starting
+	// week_start. Returns sql.ErrNoRows when there is none.
+	GetActiveDraftJobID(ctx context.Context, arg GetActiveDraftJobIDParams) (string, error)
 	// The batch still pending or running, oldest first. Returns sql.ErrNoRows
 	// when there is none.
 	GetActiveSuggestionBatch(ctx context.Context) (SuggestionBatch, error)
@@ -93,6 +97,9 @@ type Querier interface {
 	GetSuggestion(ctx context.Context, id string) (GetSuggestionRow, error)
 	// The id of the job that runs batch batch_id.
 	GetSuggestionBatchJobID(ctx context.Context, arg GetSuggestionBatchJobIDParams) (string, error)
+	// The plan of the week starting week_start. Returns sql.ErrNoRows when
+	// there is none.
+	GetWeekPlan(ctx context.Context, weekStart string) (WeekPlan, error)
 	// 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. It writes only an unarchived dinner still as it was observed
@@ -116,6 +123,13 @@ type Querier interface {
 	// first; renaming its dinner does not change it.
 	ListDeclinedSuggestionNames(ctx context.Context) ([]string, error)
 	ListDinnersByStatus(ctx context.Context, status string) ([]Dinner, error)
+	// The dinners a draft of the week starting week_start may plan: every
+	// Regular, and every Quest log dinner no other plan for the week starting
+	// from_week_start or later has on any day.
+	ListDraftPool(ctx context.Context, arg ListDraftPoolParams) ([]Dinner, error)
+	// The days of plan plan_id with their dinners, Monday first. A day with
+	// no dinner is left out.
+	ListPlanDays(ctx context.Context, planID string) ([]ListPlanDaysRow, error)
 	// The planned dinners dated from from_date up to but not including
 	// to_date, oldest first. Days with no dinner are left out.
 	ListPlannedDinners(ctx context.Context, arg ListPlannedDinnersParams) ([]ListPlannedDinnersRow, error)
@@ -131,18 +145,32 @@ type Querier interface {
 	// The Quest log: dinners with status quest_log that no plan for the week
 	// starting from_week_start or later has on any day.
 	ListUnplannedQuestLogDinners(ctx context.Context, fromWeekStart string) ([]Dinner, error)
+	// The ids of the dinners planned in the week starting week_start, Monday
+	// first.
+	ListWeekPlanDinnerIDs(ctx context.Context, weekStart string) ([]sql.NullString, error)
+	// Records an edit of plan id: a synced plan becomes changed, any other
+	// keeps its status.
+	MarkWeekPlanEdited(ctx context.Context, arg MarkWeekPlanEditedParams) error
 	// Moves a dinner still suggested to status (quest_log or archived),
 	// recording updated_by; a dinner no longer suggested is left as it is
 	// (0 rows).
 	MoveSuggestedDinner(ctx context.Context, arg MoveSuggestedDinnerParams) (int64, error)
 	// Stores a partial result of a running job.
 	PublishJobResult(ctx context.Context, arg PublishJobResultParams) (int64, error)
+	// Plans dinner_id on date of plan_id, keeping the day's calendar event id
+	// when the day exists.
+	PutPlanDay(ctx context.Context, arg PutPlanDayParams) error
+	// Records a new draft over plan id: its status and note.
+	RedraftWeekPlan(ctx context.Context, arg RedraftWeekPlanParams) error
 	// An unknown id returns sql.ErrNoRows.
 	SetDinnerFavorite(ctx context.Context, arg SetDinnerFavoriteParams) (Dinner, error)
 	// Marks a pending batch running; a batch in any other status is left as
 	// it is (0 rows).
 	StartSuggestionBatch(ctx context.Context, arg StartSuggestionBatchParams) (int64, error)
 	SucceedJob(ctx context.Context, arg SucceedJobParams) (int64, error)
+	// Plans dinner_id on an existing day of plan_id; a date the plan does not
+	// have is left as it is (0 rows).
+	SwapPlanDay(ctx context.Context, arg SwapPlanDayParams) (int64, error)
 	// An unknown id returns sql.ErrNoRows.
 	ToggleDinnerFavorite(ctx context.Context, arg ToggleDinnerFavoriteParams) (Dinner, error)
 	// An unknown id returns sql.ErrNoRows.