feat(web): dedicated full-page log viewer + run lyra-web as a service

The inline log panel is cramped, especially on mobile. Add a standalone
mobile-first log page and serve the chat server under systemd like the dream
loop (the nohup process didn't survive cleanly).

- static/logs.html: full-page live log — level filter chips, text search,
  pause/resume with buffering, autoscroll toggle, color-coded levels, and the
  expandable "view full prompt" block (where the now-note is visible in context)
- server: GET /logs serves the page (FileResponse)
- index.html: "⛶ Full Log" button opens /logs in a new tab
- deploy/lyra-web.service: user service so the chat server is reboot-resilient

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

deploy/lyra-web.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=Lyra web chat server (FastAPI + vendored UI)
+
+[Service]
+Type=simple
+WorkingDirectory=/home/serversdown/project-lyra
+UnsetEnvironment=VIRTUAL_ENV
+ExecStart=/home/serversdown/.local/bin/uv run lyra-web
+Restart=on-failure
+RestartSec=5
+
+[Install]
+WantedBy=default.target