Add SshHostCollector for .180 (omv) and .171 (ripper)

Extends monitoring to the two bare-metal boxes Proxmox can't see.
Uses a dedicated ed25519 key with a forced authorized_keys command
(see docs/ssh-collector-key-setup.md) so a leaked key can only ever
run the fixed read-only stats script, never arbitrary commands.

CPU is approximated from 1-min load average / core count (a true
utilization % would need two /proc/stat samples).

Closes #8.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/api/package.json

@@ -17,6 +17,7 @@
     "better-sqlite3": "^11.9.1",
     "dotenv": "^16.4.7",
     "fastify": "^5.2.1",
+    "ssh2": "^1.16.0",
     "undici": "^7.3.0",
     "yaml": "^2.7.0"
   },
@@ -24,6 +25,7 @@
     "@types/bcryptjs": "^2.4.6",
     "@types/better-sqlite3": "^7.6.12",
     "@types/node": "^22.13.5",
+    "@types/ssh2": "^1.15.1",
     "tsx": "^4.19.3",
     "typescript": "^5.7.3"
   }