Add Servers & Tasks module ported from Schedule Task Manager

Ports cron/systemd task tracking across Debian/Raspbian servers, including
the Linux push agent (install/report/uninstall scripts, rebranded from
"schedule-task-manager-agent" to "homelab-manager-agent") and the
manual-task-entry flow for things an agent can't see (Docker jobs, backups).
The schema (servers/scheduled_tasks tables) was already in place from the
foundation pass, so this is mostly a straight port of the original's
services/routes.

Deliberate change from the original: server/token management (which mints
agent credentials) is now admin-only rather than open to any logged-in user,
and manual task CRUD is gated to operator+ — consistent with how Secrets,
IPAM, and DNS already split "configure credentials" from "everyday edits"
across roles. All mutations are audit-logged.

- server/src/services/tokens.ts, taskSync.ts: ported near-verbatim (agent
  token hashing, the agent-sync-marks-missing-as-stale-not-deleted logic).
- server/src/routes/servers.ts, tasks.ts, agentReport.ts: same contract as
  the original (agent auth is a per-server bearer token, independent of the
  session-based requireAuth used everywhere else).
- web: a single Servers & Tasks page (filter bar, task table grouped by
  server/schedule type, manual task form, and an admin-only server
  management panel with token reveal + copyable install/uninstall commands),
  replacing the original's two separate pages/apps.

Verified: full build passes; a scripted HTTP test against a running server
covers unauthenticated access, role gating at each tier (admin-only server
mgmt, operator+ task mgmt), agent bearer-token auth (valid/invalid/rotated),
manual-vs-agent task edit protection, stale-marking on re-sync, and cascade
delete — 22/22 checks passing. Real agent installation on an actual
Debian/Raspbian host still needs to be tried on the user's network.

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

web/src/App.tsx

@@ -8,6 +8,7 @@ import AuditLog from "./pages/AuditLog";
 import Secrets from "./pages/Secrets";
 import Ipam from "./pages/Ipam";
 import Dns from "./pages/Dns";
+import ServersTasks from "./pages/ServersTasks";
 import ComingSoon from "./pages/ComingSoon";
 import AppShell from "./layout/AppShell";
 
@@ -57,7 +58,7 @@ export default function App() {
     <AppShell user={user}>
       <Routes>
         <Route path="/" element={<Dashboard user={user} />} />
-        <Route path="/servers" element={<ComingSoon title="Servers & Tasks" />} />
+        <Route path="/servers" element={<ServersTasks user={user} />} />
         <Route path="/dns" element={<Dns user={user} />} />
         <Route path="/ipam" element={<Ipam user={user} />} />
         <Route path="/secrets" element={<Secrets user={user} />} />