Add per-server admin-page links (Dockge, Webmin, Cockpit, etc.)

Each server's detail page gets an "Admin Links" card for bookmarking
that host's own web UIs -- container managers, Webmin, Cockpit, or
anything else reachable by URL -- so there's a quick way to jump
there without hunting down the address each time.

New server_links table (serverId FK, label, url, ON DELETE CASCADE so
removing a server cleans up its links automatically) and three new
routes: POST/PATCH/DELETE /api/servers/:id/links, gated to operator+
like the rest of this page's editing actions; the existing GET
/:id/detail now includes the server's links alongside hardware/DNS
info. URLs are validated to start with http:// or https:// server-side
(rejecting e.g. a javascript: URL that would otherwise render as a
clickable link).

Rendered as a row of pill buttons (label opens the URL in a new tab),
with inline edit/remove controls next to each when the viewer can
edit, and an "Add link" form matching the existing task-form style on
the same page.

Verified against a temp SQLite DB with real migrations: create/list/
update/delete all work, and deleting the parent server cascades to
remove its links rather than leaving them orphaned.

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

server/drizzle/meta/_journal.json

@@ -29,6 +29,13 @@
       "when": 1789673523898,
       "tag": "0003_fantastic_randall",
       "breakpoints": true
+    },
+    {
+      "idx": 4,
+      "version": "6",
+      "when": 1789677988329,
+      "tag": "0004_brown_gambit",
+      "breakpoints": true
     }
   ]
 }