fix: tighten the faq-bot responder and the catalogue's publish gates

[rmyndharis]

Four defects: two in how the FAQ responder decides to answer, two in what the catalogue is willing to publish.

faq-bot — answering things it cannot answer

A sticker, image or voice note arrives with an empty body. No rule can match one, so the fallback replied to a picture with "I did not understand" — and returning true claimed the event, so a plugin that could actually handle media never saw it. The guard now requires text, which is how chat-flow already guards the same hook.

The fallback cooldown slot is claimed before the send. When the send threw, the window was spent on a reply that never arrived and the chat stayed silent for its full duration — by default ten minutes. The slot is now released on failure. A message matching a rule is retried on the next message anyway, so this costs at most one send attempt per message rather than one per window.

catalog — two things nothing was checking

manifest.id was never compared to the directory name. Every path in this repo is built from the directory — the plugin folder, the zip, the release tag — while manifest.id is what the host installs under and what the catalogue publishes. A mismatch would have the download URL point at one plugin while the installed plugin called itself another.

manifest.repository had no constraint on its host, and the catalogue derives every download URL from it. Pointing it at a foreign repo would have the catalogue hand users an archive nobody here built or checksummed. The author field is deliberately unaffected — a plugin may credit anyone; the artifact has to come from a repo this project publishes.

Verification

• 582 tests pass, typecheck clean, catalog up to date, all 10 plugins build and load.
• Both catalogue gates were probed with fixture manifests: a mismatched id and a foreign repository host are each refused by name, and a correct manifest draws no complaint.
• Both faq-bot fixes are test-first; the cooldown test drives a failing send and then a working one, and would pass trivially without the fix only if the slot were never claimed.