chore: prepare isolated migration worktree

.gitignore

@@ -6,6 +6,7 @@ dist/
 playwright-report/
 test-results/
 coverage/
+.worktrees/
 !tests/fixtures/coverage/
 !tests/fixtures/coverage/below-threshold.json
 artifacts/**/*.json

docs/superpowers/plans/2026-08-15-techlog-ui-migration.md

@@ -171,14 +171,14 @@ Component and stylesheet ports must retain source file boundaries where practica
 - Create: `public/media/fetch-strategy-boundary.svg`
 - Test: `tests/features/tech-log/migration-baseline.test.ts`
 
-- [ ] **Step 1: Write the red inventory test.** Assert the pinned font/markdown packages, a 27-row expected-route manifest in the baseline document, the five source CSS filenames, and each target SVG's SHA-256 against a committed expected hash (never an external source-path read in CI). Include the source commit SHA or, if the source worktree has uncommitted changes, its HEAD SHA plus `git status --short` in the baseline document.
+- [ ] **Step 1: Write the red asset-integrity test.** Assert each target SVG's SHA-256 against a hand-recorded expected source hash (never an external source-path read in CI) and exercise the evidence asset lookup so an altered path/hash breaks a consumer-visible contract. Dependency pins are verified by the package manager's frozen-lockfile command; the human baseline document and its route/CSS inventory are reviewed rather than tested as source text. Include the source commit SHA or, if the source worktree has uncommitted changes, its HEAD SHA plus `git status --short` in the baseline document.
 - [ ] **Step 2: Run red.**
 
 ```bash
 corepack pnpm exec vitest run tests/features/tech-log/migration-baseline.test.ts
 ```
 
-Expected: dependencies/assets and TechLog route inventory are absent.
+Expected: the migrated assets and evidence lookup are absent.
 
 - [ ] **Step 3: Add exact dependencies and assets.** Run `corepack pnpm add pretendard@1.3.9 @fontsource/ibm-plex-mono@5.3.0 unified@11.0.5 remark-parse@11.0.0 remark-gfm@4.0.1 remark-directive@4.0.0`, copy only the two approved assets, and record checksums, source state, the 27 expected routes, and the five CSS files in the baseline document. Do not add Next/Vinext/Cloudflare packages.
 - [ ] **Step 4: Run green and lockfile verification.**
@@ -378,7 +378,7 @@ git commit -m "feat: add grouped TechLog route contracts"
 - Test: `tests/features/tech-log/style-contract.test.ts`
 - Test: `tests/features/tech-log/public-shell.test.tsx`
 
-- [ ] **Step 1: Add red style and interaction contracts.** Assert all source selectors/custom properties/media queries remain, only the duplicate Tailwind import is removed, CSS module class maps expose the source keys, font families resolve, header links/labels match, `/` brand navigation works, search opens by click and keyboard, Escape/focus restoration work, and dialog results navigate to canonical routes.
+- [ ] **Step 1: Add red style and interaction contracts.** Render the real shell and assert its DOM/class/ARIA relationships plus consumer-visible computed typography, color, width, spacing, focus, and minimum target behavior where the test browser supports it; media-query transitions and full computed-style/pixel equality remain Task 14 browser assertions. Assert header links/labels match, `/` brand navigation works, search opens by click and keyboard, Escape/focus restoration work, and dialog results navigate to canonical routes. Do not grep CSS source text or assert private CSS-module key inventories.
 - [ ] **Step 2: Run red.**
 
 ```bash