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>

service/rpc/mcp_cancel_double_close_test.go

@@ -0,0 +1,55 @@
+package rpc
+
+import (
+	"sync"
+	"sync/atomic"
+	"testing"
+
+	pb "github.com/nezhahq/nezha/proto"
+)
+
+// updateConfig has no serialization, so two concurrent admin PATCH /setting
+// requests can both flip EnableMCP true->false and both invoke
+// CancelAllMCPInflight concurrently. The sweep must close each entry's cancel
+// channel at most once; a non-atomic check-then-close double-closes the same
+// channel and panics, crashing the dashboard.
+func TestCancelAllMCPInflight_ConcurrentSweepsDoNotDoubleClose(t *testing.T) {
+	mcpInflight.Range(func(key, _ any) bool {
+		mcpInflight.Delete(key)
+		return true
+	})
+	t.Cleanup(func() {
+		mcpInflight.Range(func(key, _ any) bool {
+			mcpInflight.Delete(key)
+			return true
+		})
+	})
+
+	const entries = 256
+	for i := 0; i < entries; i++ {
+		mcpInflight.Store(uint64(i+1), &mcpInflightEntry{
+			serverID:  uint64(i + 1),
+			result:    make(chan *pb.TaskResult, 1),
+			cancel:    make(chan struct{}),
+			cancelled: new(atomic.Bool),
+		})
+	}
+
+	const sweepers = 8
+	var wg sync.WaitGroup
+	wg.Add(sweepers)
+	for i := 0; i < sweepers; i++ {
+		go func() {
+			defer wg.Done()
+			// A double-close inside CancelAllMCPInflight panics here and
+			// fails the test (panic in a goroutine aborts the test binary).
+			CancelAllMCPInflight()
+		}()
+	}
+	wg.Wait()
+
+	mcpInflight.Range(func(key, _ any) bool {
+		t.Fatalf("inflight entry %v survived the sweep", key)
+		return false
+	})
+}