feat(bootstrap): zero-config auto-generated secrets on first run

Resolves root cause of #252 (Electron black screen) and #249 (OAuth fail)
for users running with zero configuration (no .env needed).

New: scripts/bootstrap-env.mjs
- Auto-generates JWT_SECRET (64 bytes), STORAGE_ENCRYPTION_KEY (32 bytes),
  API_KEY_SECRET (32 bytes) if missing or empty
- Persists to {DATA_DIR}/server.env — survives restarts, Docker volume
  remounts, and upgrades without changing secrets
- Reads .env from CWD (user overrides), then merges process.env (highest prio)
- Logs friendly warnings for missing optional OAuth secrets

Updated: run-standalone.mjs + run-next.mjs
- Call bootstrapEnv() before spawning server — covers npm + Docker paths

Updated: electron/main.js (synchronous inline — CJS cannot await import ESM)
- Reads userData/server.env, generates missing secrets with crypto.randomBytes()
- Persists back to server.env, sets OMNIROUTE_BOOTSTRAPPED=true

New: BootstrapBanner.tsx + page.tsx update
- Dismissable amber banner on dashboard home when running in zero-config mode
- Shows where server.env is located and how to customize secrets

docs/openapi.yaml

@@ -1,7 +1,7 @@
 openapi: 3.1.0
 info:
   title: OmniRoute API
-  version: 2.2.4
+  version: 2.2.5
   description: |
     OmniRoute is a local-first AI API proxy router. It provides an OpenAI-compatible
     endpoint that routes requests to multiple AI providers with load balancing,