feat(sf): add type-level scaffolding for progressive planning (ADR-011)

Three additive type changes that prepare SF to wire refine-slice
through the state machine. Pure type-level — no runtime behavior
change yet:

1. types.ts:14 — Phase union gains "refining" between "planning" and
   "evaluating-gates". State derivation will yield this when a slice
   has is_sketch=1 AND phases.progressive_planning=true.

2. types.ts:354 — PhaseSkipPreferences.progressive_planning?: boolean.
   Off by default; turning it on enables sketch→refine flow.

3. sf-db.ts:2321 — SliceRow.is_sketch?: number. Column DDL not yet
   added; this just lets the type compile when migration lands.

This is the smallest forward step toward closing the refine-slice gap
identified by sf-moojsmkg-72k3ei. Next steps (separate PRs):
- DB migration: ALTER TABLE slices ADD COLUMN is_sketch INTEGER NOT
  NULL DEFAULT 0 (mirroring gsd-2 sf-db.ts:381,1074)
- state.ts: derivation rule emit phase="refining" when sketch+flag
- auto-dispatch.ts: "refining → refine-slice" rule + import
  buildRefineSlicePrompt
- Tests: progressive-planning.test.ts equivalent

Existing buildRefineSlicePrompt + prompts/refine-slice.md already in
place — only the FSM path is missing.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/resources/extensions/sf/sf-db.ts

@@ -2317,6 +2317,9 @@ export interface SliceRow {
 	replan_triggered_at: string | null;
 	/** Optional freeform scope sketch written at plan-slice time. */
 	sketch_scope?: string | null;
+	/** ADR-011: 1 = slice is a sketch awaiting refinement, 0 = full plan. Column may be absent on
+	 *  pre-migration installs (gated by phases.progressive_planning preference). */
+	is_sketch?: number;
 }
 
 function parsePlanningMeeting(raw: unknown): PlanningMeetingRecord | null {

src/resources/extensions/sf/types.ts

@@ -11,6 +11,7 @@ export type Phase =
 	| "discussing"
 	| "researching"
 	| "planning"
+	| "refining"
 	| "evaluating-gates"
 	| "executing"
 	| "verifying"
@@ -349,6 +350,10 @@ export interface PhaseSkipPreferences {
 	require_slice_discussion?: boolean;
 	/** ADR-011 Phase 2: when true, mid-execution escalation overrides are injected into the execute-task prompt. */
 	mid_execution_escalation?: boolean;
+	/** ADR-011: when true, sketch slices (slices.is_sketch=1) enter the "refining" phase
+	 *  and dispatch through refine-slice instead of plan-slice. When false (default), sketches
+	 *  are indistinguishable from missing plans and fall through to the normal "planning" phase. */
+	progressive_planning?: boolean;
 }
 
 export interface NotificationPreferences {