feat: add PBS datastore management and harden macOS keychain storage

Add Proxmox Backup Server datastore management: overview, datastore detail, download/prune/verify/GC dialogs, usePbs hook, backend commands, and tests.

Fix macOS keychain re-writes failing with 'item already exists': replace keyring 3 with keyring-core plus per-platform stores (macOS Keychain, Windows Credential Manager, Linux keyutils), recover by deleting the stale item and retrying once, and surface actionable messages for locked keychains.

src/types/connection.ts

@@ -2,6 +2,10 @@
 
 export type AuthMode = 'password' | 'token'
 
+/** The kind of server a connection targets. Absent on persisted old
+ * connections, where it is treated as 'pve'. */
+export type ServerType = 'pve' | 'pbs'
+
 export interface ConnectionConfig {
   id: string
   name: string
@@ -16,6 +20,8 @@ export interface ConnectionConfig {
   isCluster: boolean
   authMode: AuthMode
   username?: string
+  /** The kind of server this connection targets ('pve' when absent). */
+  serverType?: ServerType
   /** Nodes discovered in the cluster this connection is anchored on. */
   nodes?: DiscoveredNode[]
   /** The endpoint currently serving this connection (after failover). */

src/types/pbs.ts

@@ -0,0 +1,97 @@
+// Proxmox Backup Server (PBS) API types
+//
+// PBS exposes kebab-case JSON fields; the Rust backend maps them to camelCase
+// structs (serde `rename_all = "camelCase"`), so these types mirror the
+// backend's shapes. All fields are optional unless marked required.
+
+export interface PbsDatastore {
+  store: string // required
+  comment?: string
+  backendType?: string // 'filesystem' | 's3'
+  mountStatus?: string // 'mounted' | 'notmounted' | 'nonremovable'
+  maintenance?: string
+  total?: number
+  used?: number
+  avail?: number
+  error?: string
+  estimatedFullDate?: number
+  history?: number[]
+  gcStatus?: {
+    diskBytes?: number
+    diskChunks?: number
+    indexDataBytes?: number
+    indexFileCount?: number
+    pendingBytes?: number
+    pendingChunks?: number
+    removedBad?: number
+    removedBytes?: number
+    removedChunks?: number
+    stillBad?: number
+    cacheHits?: number
+    cacheMisses?: number
+    upid?: string
+  }
+}
+
+export interface PbsVersion {
+  version: string
+  release: string
+  repoid: string
+}
+
+export interface PbsNodeStatus {
+  cpu?: number
+  loadavg?: number[]
+  uptime?: number
+  memory?: { free?: number; total?: number; used?: number }
+  root?: { avail?: number; total?: number; used?: number }
+  swap?: { free?: number; total?: number; used?: number }
+  cpuinfo?: { cpus?: number; model?: string; sockets?: number }
+  currentKernel?: { machine?: string; release?: string; sysname?: string; version?: string }
+}
+
+export interface PbsBackupGroup {
+  backupId: string // required, e.g. "100"
+  backupType: 'vm' | 'ct' | 'host'
+  backupCount?: number
+  lastBackup?: number // unix epoch
+  comment?: string
+  files?: string[]
+}
+
+export interface PbsSnapshot {
+  backupId: string // required
+  backupType: 'vm' | 'ct' | 'host'
+  backupTime: number // required, unix epoch
+  size?: number
+  protected?: boolean
+  comment?: string
+  files?: string[]
+  fingerprint?: string
+  owner?: string
+  verification?: { state?: 'ok' | 'failed'; upid?: string }
+}
+
+export interface PbsSnapshotFile {
+  filename: string
+  size?: number
+  cryptMode?: string
+}
+
+export interface PbsJob {
+  id: string // required
+  store?: string
+  schedule?: string
+  comment?: string
+  disable?: boolean
+  lastRunState?: string
+  lastRunEndtime?: number
+  nextRun?: number
+  keepLast?: number
+  keepDaily?: number
+  keepWeekly?: number
+  keepMonthly?: number
+  keepYearly?: number
+  ignoreVerified?: boolean
+  maxDepth?: number
+}