feat(dashboard): show build git SHA in header + profile page

The version label now renders 'v0.5.86 (<shortsha>)' when the flake build
injects NEXT_PUBLIC_GIT_SHA (git commit identity of the deployed artifact),
so any running dashboard traces to its exact source commit. Falls back to
semver-only when the env var is absent (local dev). Also fixes the profile
page repo link back to asepharyana/9router (MIBP merge target), replacing
the mhiqrambg fork label left over from the merge.

src/shared/constants/config.js

@@ -5,6 +5,10 @@ export const APP_CONFIG = {
   name: "9Router Proxy",
   description: "AI Infrastructure Management",
   version: pkg.version,
+  // Build identity = git short SHA, injected at build time by the Nix flake
+  // (NEXT_PUBLIC_GIT_SHA). Falls back to "dirty"/undefined in dev where the
+  // env var is absent, so the dashboard shows just the semver.
+  gitSha: process.env.NEXT_PUBLIC_GIT_SHA || null,
 };
 
 // GitHub configuration