[Bug] useTriggerMenu closes @ menus when the query contains whitespace

[testikun]

Description

useTriggerMenu stops scanning an active trigger as soon as it encounters a space or newline. That single-token grammar is appropriate for / commands, but it prevents @ menus from searching multi-word entity names and prevents a trailing @ from keeping the complete reference list open.

Consumers currently have no option to configure whitespace behavior per trigger. Maka therefore carries a local @astryxdesign/core@0.5.2 patch for its Composer Session-reference picker. A public trigger option or built-in distinction between / and @ would let that patch be removed.

Expected behavior: a trigger can opt into queries containing whitespace. Slash-command behavior should remain unchanged by default.

Reproduction

1. Configure useTriggerMenu with both / and @ triggers.
2. Open the @ menu and type @Project Alpha, or type @ to browse all reference candidates.
3. Observe that the active trigger is cleared at the first space, so the menu closes and cannot match the multi-word name.
4. The same single-token behavior is desirable for /command args, so changing the global scanner without a per-trigger policy would regress slash commands.

Astryx Version

@astryxdesign/core@0.5.2

Environment

Electron 43 / Chromium, macOS. The behavior is in the trigger parser and is not platform-specific.

Downstream context: apache/maka#4446.