Show the build's version and commit in Settings

vite.config.ts stamps the package version, git commit and build time
into the bundle as __BUILD__, and the Settings sidebar shows
"v0.1.0 · <short sha>" (full sha and build time on hover). The Docker
build has no git binary, so the commit is read from .git/HEAD and the
refs directly; .dockerignore now lets just those files through.
GIT_COMMIT in the environment overrides detection.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GaoZtJQZwLXkEgWs8twCia

src/app.d.ts

@@ -1,6 +1,9 @@
 // See https://svelte.dev/docs/kit/types#app.d.ts
 declare global {
 	namespace App {}
+
+	/** Stamped in by vite.config.ts at build time. */
+	const __BUILD__: { version: string; commit: string; dirty: boolean; time: string };
 }
 
 export {};