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>

model/server_transfer.go

@@ -81,11 +81,21 @@ type ServerTransfer struct {
 // admins, the source user, the destination user, and the initiator. Listing
 // uses this to filter what the caller can see; mutating endpoints (cancel,
 // retry) layer additional checks on top.
+//
+// PAT server_ids whitelist is evaluated FIRST, before the admin short-
+// circuit, so an admin-issued PAT scoped to a subset of servers cannot
+// widen reach by virtue of the caller being an admin. JWT callers (no PAT
+// in context) skip the whitelist check.
 func (t *ServerTransfer) HasPermission(ctx *gin.Context) bool {
 	auth, ok := ctx.Get(CtxKeyAuthorizedUser)
 	if !ok {
 		return false
 	}
+	if v, ok := ctx.Get(CtxKeyAPIToken); ok {
+		if tok, _ := v.(APITokenAccessor); tok != nil && !tok.CanAccessServer(t.ServerID) {
+			return false
+		}
+	}
 	user := *auth.(*User)
 	if user.Role == RoleAdmin {
 		return true