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/singleton/server_delete_missing_test.go

@@ -0,0 +1,32 @@
+package singleton
+
+import (
+	"testing"
+
+	"github.com/nezhahq/nezha/model"
+)
+
+func TestServerClassDeleteMissingIDNoPanic(t *testing.T) {
+	c := &ServerClass{
+		class: class[uint64, *model.Server]{
+			list: map[uint64]*model.Server{
+				1: {Common: model.Common{ID: 1}, UUID: "uuid-1"},
+			},
+		},
+		uuidToID: map[string]uint64{"uuid-1": 1},
+	}
+
+	c.Delete([]uint64{999999})
+
+	if _, ok := c.list[1]; !ok {
+		t.Fatalf("existing server 1 must remain after deleting a non-existent id")
+	}
+
+	c.Delete([]uint64{1, 424242})
+	if _, ok := c.list[1]; ok {
+		t.Fatalf("server 1 should be removed")
+	}
+	if _, ok := c.uuidToID["uuid-1"]; ok {
+		t.Fatalf("uuid mapping for server 1 should be removed")
+	}
+}