feat(overlay): add in-app changelog modal

- Add a changelog modal opened from tray "View Changelog" or the update notification's "What's New" button; renders in-player or in its own window like the help modal
- Fetch changelog from the newest published release so newer-than-installed notes are visible, falling back to the bundled CHANGELOG.md on failure
- Group versions by minor line (current expanded, older folded), badge the installed version, tag newer ones "New"
- Support J/K/arrow navigation, Enter to fold/unfold, R to refetch, Esc to close
- Add changelog parsing/semver-compare utils and changelog IPC channel/runtime; bundle CHANGELOG.md into packaged builds
- Replace release/release-notes.md with changes/changelog-modal.md changeset entry

src/main/runtime/tray-runtime.ts

@@ -32,6 +32,7 @@ export function resolveTrayIconPathRuntime(deps: {
 export type TrayMenuActionHandlers = {
   platform?: string;
   openSessionHelp: () => void;
+  openChangelog: () => void;
   openTexthookerInBrowser: () => void;
   showTexthookerPage: boolean;
   openFirstRunSetup: () => void;
@@ -72,6 +73,10 @@ export function buildTrayMenuTemplateRuntime(handlers: TrayMenuActionHandlers):
       label: 'Open Help',
       click: handlers.openSessionHelp,
     },
+    {
+      label: 'View Changelog',
+      click: handlers.openChangelog,
+    },
     ...(handlers.showTexthookerPage
       ? [
           {