dsh-tabbit 0.4.0

• The @ menu gains a dedicated "标签组" (tab groups) section: groups are
  first-class candidates, aggregated live from the browser's tab inventory,
  and can also be found by their member pages' titles/URLs. A group mention
  is a lightweight reference, not a send-time extraction — the chip carries
  the group's member list and sending stays instant; the injected
  <browser-tab-group> context guides the model to pull the pages it needs
  with tabbit_browser/web_fetch (visible, permission-gated) instead of
  blocking the send on a multi-page re-fetch. Single-page mentions keep
  their send-time extraction unchanged.
• Tab-group home pages (web.tabbit.ai/group-home/...) no longer appear in
  the "网页标签" (web tabs) candidates — they are empty shells with no
  extractable content.
• Adapted the injected context message to DSH 0.2's message-source contract:
  the shared catch-all plugin source kind was removed, so the injected
  message now carries the plugin's own dsh-tabbit kind, registered through
  module augmentation. Both host generations render unknown kinds as the
  same collapsed injection row.