feat(auth): add PAT auth, scoped REST/MCP access, CSRF, and tenant isolation

Introduce Personal Access Tokens (nzp_*) as a stateless auth path alongside
JWT, gated per-endpoint by a scope middleware (nezha:{resource}:{verb}) with
fail-closed empty-scope defaults and a server-id whitelist. Self-management
endpoints (profile, api-tokens, oauth2 bind, refresh-token) explicitly reject
PATs to block privilege-escalation chains. A revoke registry tears down active
long-lived connections (terminal, fm, ws, transfer, mcp) the moment a PAT is
deleted, with a tombstone closing the revoke->register race.

Add an MCP endpoint that proxies tool calls (exec, fs read/write/delete,
transfer) to agents over gRPC, guarded by origin/DNS-rebinding checks, a
per-token rate limiter, audit logging, and a kill switch. Serialize all
sends through the IOStream wrapper to honour grpc-go's concurrency contract.

Add CSRF double-submit protection on unsafe cookie-authenticated methods,
exempting authenticated PAT requests by context identity (not a forgeable
Authorization header). Apply visibility/whitelist filtering consistently
across list, get-by-id, and mutate paths to enforce tenant isolation.

Migrate legacy mcp:* scopes: rewrite read/exec to nezha:* equivalents and
drop dangerous write/delete/wildcard grants.

Co-authored-by: cloudcode <cloudcode@users.noreply.github.com>

cmd/dashboard/main.go

@@ -101,6 +101,13 @@ func initIDCodec() error {
 // @securityDefinitions.apikey  BearerAuth
 // @in header
 // @name Authorization
+// @description JWT session token. Browser/UI flow. Format: `Bearer <jwt>` or cookie `nz-jwt`.
+
+// @securityDefinitions.apikey  APITokenAuth
+// @in header
+// @name Authorization
+// @description Personal Access Token (PAT). Programmatic/CI/LLM flow. Format: `Bearer nzp_<secret>`.
+// @description Each endpoint enforces a specific scope; see the `controller` package godoc for the authoritative scope table.
 
 // @externalDocs.description  OpenAPI
 // @externalDocs.url          https://swagger.io/resources/open-api/
@@ -140,6 +147,9 @@ func main() {
 
 	singleton.CleanMonitorHistory()
 	rpc.DispatchKeepalive()
+	rpc.SetMCPKillSwitchObserver(func() bool {
+		return singleton.Conf == nil || !singleton.Conf.MCPEnabled()
+	})
 	go rpc.DispatchTask(serviceSentinelDispatchBus)
 	go singleton.AlertSentinelStart()