Phase 008: close the test and CI loop around the migration

Adds the checks that make the constraints from Phase 001-007 mechanical
instead of tribal knowledge, and clears the legacy brand text that was still
reachable at runtime.

New red-line tests:
  - no-legacy-brand mirrors the harness scan under vitest, and asserts its
    allow-list has not drifted from harness-check.mjs
  - hermes-db-readonly classifies every new DatabaseSync call site by
    following the path it opens, and fails if a state.db handle drops
    readOnly. It also pins the one legitimately writable database.
  - i18n-parity compares the raw zh/en locale objects both ways. The
    existing coverage test merged en into zh at import time, so a key
    missing from zh could never fail there.

harness:check gains the four missing gates from the phase brief - retired
package directories, retired package scripts, a single UI library, and the
required root files. Each was verified to fail by mutating the repo.

The online-update channel had hardcoded upstream URLs. It now reads
HERMES_WEB_UI_VERSION_MANIFEST_URL and friends and degrades with a named
error, because a reimplementation has nowhere to pull releases from.

The remaining legacy strings are deliberate and each carries a reason in the
allow-list: the global-agent relay address and the OpenRouter referer are
load-bearing, the socket role identifier is a wire contract, and the pre-rename
DB filenames would orphan existing deployments if changed. AGENTS.md now says
so explicitly, so a future agent does not "clean them up".

Also removes a dead electron mock alias, an i18n exemption that had stopped
exempting anything, and a teardown race in plugins-view.test.ts where a-spin
animation frames outlived the jsdom environment.

Verified self-contained: with reference_code/ moved aside, harness:check,
build, test and test:e2e all pass, so the directory can now be deleted.

.github/ISSUE_TEMPLATE/config.yml

@@ -1,8 +1 @@
 blank_issues_enabled: true
-contact_links:
-  - name: Documentation
-    url: https://github.com/EKKOLearnAI/hermes-studio#readme
-    about: Please check the documentation first
-  - name: GitHub Discussions
-    url: https://github.com/EKKOLearnAI/hermes-studio/discussions
-    about: Use GitHub Discussions for questions that don't fit as issues

.github/workflows/build.yml

@@ -44,5 +44,11 @@ jobs:
       - name: Test with coverage
         run: npm run test:coverage
 
+      - name: Install Playwright browsers
+        run: npx playwright install --with-deps chromium
+
+      - name: End-to-end tests
+        run: npm run test:e2e
+
       - name: Build
         run: npm run build