Add Synology integration — completes all six planned live integrations

Sixth and final live integration: volume and disk health across the NAS,
read-only per the delivery plan (DSM write actions are riskier and stayed
out of scope). Adapter built against the same discover-then-call pattern
used by hacf-fr/synologydsm-api (the library behind Home Assistant's
Synology integration) since DSM's API paths/versions vary by release and
the user's NAS isn't reachable from here to check directly:
- GET query.cgi?api=SYNO.API.Info&method=query&query=all once per adapter
  instance, to learn the real path/version for SYNO.API.Auth and
  SYNO.Storage.CGI.Storage rather than hardcoding them
- SYNO.API.Auth login (account/passwd/format=sid) for a session id, re-used
  across calls and refreshed on session-related error codes (105/106/119)
- SYNO.Storage.CGI.Storage's `load_info` method, which returns disks,
  volumes, and pools in one call — verified against that library's
  storage.py field mapping (size.total/used, status, smart_status, temp,
  exceed_bad_sector_thr, below_remain_life_thr)

Uses node:https directly (like Proxmox and the cPanel DNS adapter) for an
"allow self-signed certificate" option, since DSM ships one by default.
No 2FA support — login surfaces a clear error if the account requires it
rather than failing silently.

Verified: full build passes. Unreachable from here, so ran an 11-check HTTP
test against the live server: confirms all six integration types are now
registered, role gating, credential (password) non-leakage, disabled-
integration blocking, and the wrong_type crash-safety check — server stays
up throughout. Real volume/disk data still needs verification once this app
can reach the user's NAS.

This completes the integrations phase from the original plan: Tailscale,
Gitea, Dockhand, Semaphore, Proxmox, Synology are all built, each following
the same config-in-UI + encrypted-credentials pattern. Combined with the
foundation, Secrets, IPAM, DNS, and Servers & Tasks modules from earlier,
Homelab Manager now covers every feature area from the user's original
request.

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

server/src/integrations/fieldSchemas.ts

@@ -33,6 +33,12 @@ export const INTEGRATION_FIELDS: Partial<Record<IntegrationType, IntegrationFiel
     { key: "tokenSecret", label: "API token secret", secret: true, type: "password" },
     { key: "insecure", label: "Allow self-signed certificate", secret: false, type: "checkbox" },
   ],
+  synology: [
+    { key: "url", label: "Synology DSM URL", secret: false, placeholder: "https://nas.example.lan:5001" },
+    { key: "username", label: "Username", secret: false },
+    { key: "password", label: "Password", secret: true, type: "password" },
+    { key: "insecure", label: "Allow self-signed certificate", secret: false, type: "checkbox" },
+  ],
 };
 
 /** Fixed base URL per integration type, stored on the row for display/reference. */