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).

src/config/settingsCredits.ts

@@ -160,6 +160,7 @@ const CONTRIBUTOR_ENTRIES = [
       'Library DB: named slow-write op labels for macOS playback-stall diagnosis (PR #1043)',
       'Settings → Servers: compact two-line cards, capability header badges, unified use/active action, delete in edit form, click-pinned version tooltip (PR #1054)',
       'Navidrome Now Playing and scrobble with hot cache, offline pins, and mixed-server playback reachability (PR #1055)',
+      'What\'s New: remote WHATS_NEW.md from release assets, dev workspace mode, Highlights vs changelog tabs (PR #1058)',
     ],
   },
   {