Add a "Sync from Proxmox" action to IP Addresses (IPAM)

Extends the Tailscale IPAM sync to Proxmox: pulls every VM/LXC's IP
address(es) across all enabled Proxmox integrations into the
inventory, reusing the same never-overwrite-a-manual-entry semantics.

Proxmox guests can have multiple NICs (each IP synced as its own
entry) and, for QEMU VMs, IP discovery depends on a responsive guest
agent — a VM with none simply contributes zero entries rather than
erroring, matching getGuestDetail()'s existing best-effort behavior.
listGuests() doesn't include IPs, so this fetches getGuestDetail() per
guest; acceptable for an explicit, user-triggered sync rather than a
background poll.

Extracted the shared "insert, update only if I own this row, else
skip and report" upsert logic (previously inline in the Tailscale sync
handler) into upsertSyncedEntry(), now used by both sync routes so the
core safety rule can't drift between them.

Verified end-to-end against a mock Proxmox server covering: an LXC
with two NICs (both synced), a QEMU VM with a responsive guest agent,
a QEMU VM with no agent (zero entries, no error), a manual-entry
collision (skipped and reported, never overwritten), and idempotent
re-sync (add -> update on the second run).

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

web/src/api/client.ts

@@ -69,7 +69,7 @@ export interface IpamEntry {
   matchingDnsRecords: string[];
 }
 
-export interface TailscaleSyncResult {
+export interface IpamSyncResult {
   added: number;
   updated: number;
   skipped: number;
@@ -488,7 +488,8 @@ export const api = {
     update: (id: number, data: Partial<Omit<IpamInput, "ipAddress">>) =>
       request<{ entry: IpamEntry }>(`/api/ipam/${id}`, { method: "PATCH", body: JSON.stringify(data) }),
     remove: (id: number) => request<void>(`/api/ipam/${id}`, { method: "DELETE" }),
-    syncTailscale: () => request<TailscaleSyncResult>("/api/ipam/sync-tailscale", { method: "POST" }),
+    syncTailscale: () => request<IpamSyncResult>("/api/ipam/sync-tailscale", { method: "POST" }),
+    syncProxmox: () => request<IpamSyncResult>("/api/ipam/sync-proxmox", { method: "POST" }),
   },
   dns: {
     providerFields: () =>