feat: add token auth, login page, skill toggle, and route restructure

- Add token-based authentication with auto-generated token stored in server/data/.token
- Add login page with URL token auto-fill support
- Add route guards requiring auth for all pages except login
- Restructure routes: / for login, /chat for conversations
- Add skill enable/disable toggle via config.yaml skills.disabled
- Unify logo to /logo.png across sidebar, login, messages, and empty state
- Hide sidebar on login page, prevent flash with router.isReady()
- Fix session export JSON parse error when CLI returns non-JSON output
- Display token in CLI on server start

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/services/hermes-cli.ts

@@ -137,6 +137,8 @@ export async function getSession(id: string): Promise<HermesSession | null> {
     const lines = stdout.trim().split('\n').filter(Boolean)
     if (lines.length === 0) return null
 
+    if (!lines[0].startsWith('{')) return null
+
     const raw: HermesSessionFull = JSON.parse(lines[0])
     return {
       id: raw.id,