feat: design taste engine with persistent schema

Adds a cross-session taste profile that learns from design-shotgun
approval/rejection decisions. Biases future design-consultation and
design-shotgun proposals toward the user's demonstrated preferences.

Codex review caught that the plan had "taste engine" as a vague goal
without schema, decay, migration, or placeholder insertion points. This
commit ships the full spec.

Schema v1 at ~/.gstack/projects/$SLUG/taste-profile.json:
- version, updated_at
- dimensions: fonts, colors, layouts, aesthetics — each with approved[]
  and rejected[] preference lists
- sessions: last 50 (FIFO truncation), each with ts/action/variant/reason
- Preference: { value, confidence, approved_count, rejected_count, last_seen }
- Confidence: Laplace-smoothed approved/(total+1)
- Decay: 5% per week of inactivity, computed at read time (not write)

Changes:
- bin/gstack-taste-update: new CLI. Subcommands approved/rejected/show/
  migrate. Parses reason string for dimension signals (e.g.,
  "fonts: Geist; colors: slate; aesthetics: minimal"). Emits taste-drift
  NOTE when a new signal contradicts a strong opposing signal. Legacy
  approved.json aggregates migrate to v1 on next write.
- scripts/resolvers/design.ts: new generateTasteProfile() resolver.
  Produces the prose that skills see: how to read the profile, how to
  factor into proposals, conflict handling, schema migration.
- scripts/resolvers/index.ts: register TASTE_PROFILE and a BIN_DIR
  resolver (returns ctx.paths.binDir, used by templates that shell out
  to gstack-* binaries).
- design-consultation/SKILL.md.tmpl: insert {{TASTE_PROFILE}} placeholder
  in Phase 1 right after the memorable-thing forcing question so the
  Phase 3 proposal can factor in learned preferences.
- design-shotgun/SKILL.md.tmpl: taste memory section now reads
  taste-profile.json via {{TASTE_PROFILE}}, falls back to per-session
  approved.json (legacy). Approval flow documented to call
  gstack-taste-update after user picks/rejects a variant.

Known gap: v1 extracts dimension signals from a reason string passed
by the caller ("fonts: X; colors: Y"). Future v2 can read EXIF or an
accompanying manifest written by design-shotgun alongside each variant
for automatic dimension extraction without needing the reason argument.

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

scripts/resolvers/index.ts

@@ -9,7 +9,7 @@ import type { TemplateContext, ResolverFn } from './types';
 import { generatePreamble } from './preamble';
 import { generateTestFailureTriage } from './preamble';
 import { generateCommandReference, generateSnapshotFlags, generateBrowseSetup } from './browse';
-import { generateDesignMethodology, generateDesignHardRules, generateDesignOutsideVoices, generateDesignReviewLite, generateDesignSketch, generateDesignSetup, generateDesignMockup, generateDesignShotgunLoop } from './design';
+import { generateDesignMethodology, generateDesignHardRules, generateDesignOutsideVoices, generateDesignReviewLite, generateDesignSketch, generateDesignSetup, generateDesignMockup, generateDesignShotgunLoop, generateTasteProfile } from './design';
 import { generateTestBootstrap, generateTestCoverageAuditPlan, generateTestCoverageAuditShip, generateTestCoverageAuditReview } from './testing';
 import { generateReviewDashboard, generatePlanFileReviewReport, generateSpecReviewLoop, generateBenefitsFrom, generateCodexSecondOpinion, generateAdversarialStep, generateCodexPlanReview, generatePlanCompletionAuditShip, generatePlanCompletionAuditReview, generatePlanVerificationExec, generateScopeDrift, generateCrossReviewDedup } from './review';
 import { generateSlugEval, generateSlugSetup, generateBaseBranchDetect, generateDeployBootstrap, generateQAMethodology, generateCoAuthorTrailer, generateChangelogWorkflow } from './utility';
@@ -64,4 +64,6 @@ export const RESOLVERS: Record<string, ResolverFn> = {
   CROSS_REVIEW_DEDUP: generateCrossReviewDedup,
   DX_FRAMEWORK: generateDxFramework,
   MODEL_OVERLAY: generateModelOverlay,
+  TASTE_PROFILE: generateTasteProfile,
+  BIN_DIR: (ctx) => ctx.paths.binDir,
 };