feat(appshots): redesign App Shots tab as a batch flow with per-shot copy edits

[hanrw]

Summary

Redesigns the App Shots tab from a single-shot editor into a batch-first workspace that matches the customer ask: "press a button, capture a few screens, get 8 polished template sets."

Journey

• Hero on first visit — big CTA in an empty project; auto-skipped once sets exist.
• Workspace — three-column persistent layout: Captures · Sets · Inspector. Capture/Record/Upload on the left; 8 template cards in the center; default headline/subtitle/frame on the right.
• Parallel fan-out — 8 templates × N captures via AppShotsGenerator with a 4-way concurrency cap (ASC plugin can't handle ~48 parallel apply calls).
• Persistent sets grid — returning visits land on the 8-set grid, rehydrated from disk.
• Detail sheet — click a set to see every shot full-size in a horizontal scroll. Each shot has inline Headline / Subtitle / Tagline / App name fields; hit Return to re-render just that shot.
• Upload to ASC — prominent primary in the detail sheet (wiring TBD).

Rich domain

• GeneratedScreenshot owns its copy (effectiveHeadline, effectiveSubtitle, effectiveTagline, effectiveAppName), sourceScreenshot, and canRender — so edits + retries work without a live CapturedShot (which isn't persisted).
• PersistedSets v4 carries all four text slots + source path per shot. Older format files are ignored → user re-onboards.
• AppShotsFlowManager (state machine) + service layer (Generator, Store, Capture, DeviceFrameCompositor, Copywriter) + 4 view files.

Quality of life

• Checkbox per capture + auto-exclude near-blank screens (downsampled luminance heuristic).
• Device-frame compositing restored (insets.json + bundled iPhone 16/17 frames).
• Retry button + applyShotChanges unifies "retry failed" and "apply edited copy."
• Two-surface color token system (canvas + cardSurface) — consistent in light & dark mode.

Files

src/models/AppShotsDomain.swift                   value types + domain behavior
src/services/appshots/
  AppShotsCapture.swift                           snap + FlowRecorder
  AppShotsCopywriter.swift                        per-category subtitle bank
  AppShotsGenerator.swift                         throttled template fan-out
  AppShotsStore.swift                             persistence (v4)
  DeviceFrameCompositor.swift                     bezel overlay
src/managers/app/AppShotsFlowManager.swift        @Observable state machine
src/views/build/AppShotsView.swift                thin tab entry (hero vs workspace)
src/views/build/appshots/
  AppShotsAtoms.swift                             tokens, SetCard, ShotCopyEditor, Sheet
  AppShotsHeroView.swift
  AppShotsWorkspaceView.swift                     toolbar + captures/sets/inspector panels

Test plan

• First-visit: App Shots tab shows hero with "Get started" CTA
• Capture 3+ screens → default headline in Inspector → "Generate 8 sets" renders 8 templates in parallel
• Near-blank capture gets auto-excluded with a warning icon; checkbox toggles inclusion
• Reopen app: lands on the 8-set grid (not hero)
• Click a set → detail sheet shows all N shots in a horizontal scroll with editable headline/subtitle/tagline/app name
• Edit a headline → Return → just that shot re-renders with new copy, others untouched
• Failed shot shows the orange "Render failed" tile; retry icon re-runs that single render
• Reset button clears captures + sets + persisted file → back to hero
• Light-mode and dark-mode both render cleanly