feat(auth): split inventory scope out of server scope

Carve a new nezha:inventory:{read,delete,*} resource family out of
nezha:server:*. Listing and deleting servers/server-groups (GET /server,
/server-group, /ws/server, batch-delete/server[-group], MCP server.list)
now require nezha:inventory:*, while nezha:server:* covers per-server
runtime operations (get, exec, fs, config, metrics, batch-move,
force-update).

Also declare MCP tool OutputSchema for exec/fs/meta/server/transfer and
wrap server.list output in {servers,count} so strict MCP clients accept
the structured result. Correct the /file all-of scope entry and the stale
server:read documentation.

cmd/dashboard/controller/mcp_tools_meta.go

@@ -27,6 +27,18 @@ func init() {
 			"type":       "object",
 			"properties": map[string]any{},
 		},
+		OutputSchema: map[string]any{
+			"type": "object",
+			"properties": map[string]any{
+				"user_id":    map[string]any{"type": "integer"},
+				"is_admin":   map[string]any{"type": "boolean"},
+				"token_id":   map[string]any{"type": "integer"},
+				"token_name": map[string]any{"type": "string"},
+				"scopes":     map[string]any{"type": "array", "items": map[string]any{"type": "string"}},
+				"server_ids": map[string]any{"type": "array", "items": map[string]any{"type": "integer"}},
+			},
+			"required": []string{"user_id", "is_admin", "token_id", "scopes"},
+		},
 		RequiredScope: "",
 		Handler:       handleMetaWhoami,
 	})