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/mcp_classify_disabled_test.go

@@ -0,0 +1,28 @@
+package controller
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/nezhahq/nezha/model"
+	"github.com/nezhahq/nezha/service/rpc"
+)
+
+// classifyToolError 必须把 rpc.ErrMCPDisabled 归类成 forbidden 类 outcome，而不是
+// 当作 agent_error。
+//
+// ErrMCPDisabled 是 dashboard 主动按下 kill switch 的语义信号（见
+// service/rpc/mcp_rpc.go 注释），controller 把它揉进 agent_error 等于把“管理员
+// 关了 MCP”和“agent 真出故障”混在一起：审计日志、SIEM 告警和 MCP 客户端的
+// structuredContent.error_code 都会错配。
+func TestClassifyToolError_MCPDisabledMapsToForbidden(t *testing.T) {
+	code, msg := classifyToolError(rpc.ErrMCPDisabled)
+
+	assert.Equal(t, model.MCPOutcomeMCPDisabled, code,
+		"rpc.ErrMCPDisabled must map to MCPOutcomeMCPDisabled, not agent_error")
+	assert.NotEqual(t, model.MCPOutcomeAgentError, code,
+		"kill-switch errors must not be reported as agent_error in audit/SIEM")
+	assert.Contains(t, msg, "MCP is disabled",
+		"error text should preserve the kill switch reason")
+}