feat(whats-new): remote release notes with dev workspace mode (#1058)

* feat(whats-new): remote release notes with dev workspace mode

Add WHATS_NEW.md, CI whats-new.md asset upload, and client fetch/cache
with embedded fallbacks. Dev and -dev builds read the full file from the
repo for debugging; RC/stable download the release asset on first use.

* fix(whats-new): render ## headings and add changelog tab

Parse h2 sections in release-notes markdown; load changelog alongside
highlights and let users switch views on the What's New page.

* fix(whats-new): prefetch on startup and fix CI typecheck prebuild

Prefetch whats-new asset when the shell loads on RC/stable builds.
Run prebuild:release-notes before tsc and coverage jobs so the
gitignored generated bundle exists in CI.

* docs: CHANGELOG and credits for What's New remote notes (PR #1058)

* fix(whats-new): always slice embedded release notes to current line

Drop full CHANGELOG embed for -dev bundles; tauri:dev still reads live
markdown from the repo. Ignore all of src/generated/ in git.

* fix(whats-new): fetch release asset via Rust to bypass CORS

Route whats-new.md download through fetch_url_bytes; rename the
technical tab label; add fetch unit tests (PR #1058 review).

.github/workflows/frontend-tests.yml

@@ -56,6 +56,7 @@ jobs:
           node-version: 'lts/*'
           cache: 'npm'
       - run: npm ci
+      - run: npm run prebuild:release-notes
       - name: tsc
         run: npx tsc --noEmit
 
@@ -71,6 +72,7 @@ jobs:
       - name: install jq
         run: sudo apt-get update && sudo apt-get install -y jq
       - run: npm ci
+      - run: npm run prebuild:release-notes
       - name: vitest run --coverage
         run: npx vitest run --coverage
       - name: hot-path file coverage gate