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/controller/frontend_fallback_api_tokens_test.go

@@ -0,0 +1,25 @@
+package controller
+
+import (
+	"net/http"
+	"strings"
+	"testing"
+)
+
+// 前端在 main.tsx 注册了 /dashboard/settings/api-tokens，但后端 fallback 白名单
+// 漏加这条会让用户直接刷新该页面拿到 HTTP 404（body 还是 index.html）。
+// controller.go 旁边的注释明确说「新增前端路由时必须在 main.tsx 与这里同步加」。
+func TestFallbackToFrontend_APITokensRouteReturns200(t *testing.T) {
+	t.Chdir(t.TempDir())
+	router := newFrontendFallbackTestRouter(t)
+
+	w := performFrontendFallbackRequest(t, router, "/dashboard/settings/api-tokens")
+	if w.Code != http.StatusOK {
+		t.Fatalf("/dashboard/settings/api-tokens fallback status = %d, want 200 "+
+			"(front-end main.tsx registered the route — backend SPA fallback regex must mirror it)",
+			w.Code)
+	}
+	if !strings.Contains(w.Body.String(), "admin index") {
+		t.Fatalf("/dashboard/settings/api-tokens must serve admin index.html, got %q", w.Body.String())
+	}
+}