#15 Desktop packaging and labels, undo/redo, GitHub Pages, and unified styling

[Anonymous]

Originally created by: athanclark

Stacked on [#14], which covers [#2]–#7. This PR handles the remaining open issues.

• #9 AppImage: adds a linux-appimage release target, built on Ubuntu 24.04 (the native store needs SQLite 3.39+). It is listed in both download menus and required by release validation. I built it locally: the AppImage bundles SQLite and WebKitGTK, and libgmp stays on linuxdeploy's host-provided exclude list.
• #10 Desktop file actions: the desktop buttons are now Open, Save and Save As…. SQLite wording is also gone from status text, the file-dialog filter and native error messages.
• #11 Sign in: on desktop, the Sign in button stays disabled, with a tooltip, until a server connection reports itself available.
• #12 Undo/Redo: adds a redo stack, which any new edit clears, and a Redo button. Ctrl/⌘+Z, Ctrl/⌘+Shift+Z and Ctrl+Y work outside text fields, so native text undo is unaffected.
• #13 GitHub Pages: the new pages.yml workflow builds the offline HTML on each push to main, runs the offline browser test, and publishes it as index.html of openchronology/openchronology.github.io (https://openchronology.github.io/). It pushes with a write deploy key scoped to that repo (secret PAGES_DEPLOY_KEY, already configured) and leaves the other site files untouched.
• #8 Styling: buttons, inputs, labels, links, dialogs and menus now share one set of design tokens, in both the editor and the Next.js platform. Inputs no longer inherit bold label text, and interface text no longer drops to 8–10px. Chart marker and label geometry is unchanged.

Validation, run locally: typecheck, 160 unit tests, the Next.js build and test:platform, and the served and offline browser suites in Chromium (including new redo, keyboard-shortcut and desktop sign-in/label assertions). I also ran the desktop cache browser test and a local AppImage build. Firefox and WebKit are left to CI.

Fixes [#8]
Fixes [#9]
Fixes [#10]
Fixes [#11]
Fixes [#12]
Fixes [#13]

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https://claude.ai/code/session_01Ti36soiZpKdSxKfvQLEcfY

[Anonymous]

Ticket changed by: athanclark

• status: open --> closed