webclient: make session loads cheap, cancellable and honest ...

Opening a session moved ~1 MB of history JSON and a 1.5 MB bundle
uncompressed, then reloaded the whole transcript on every WebSocket
reconnect; a failed request wiped what was on screen.

Server: GZipMiddleware(1 KB) - one history page shrinks 5.1x, the SPA
bundle 3.2x.

Client:
- session_sync asks /meta instead of reloading history, and only when
  the view is idle;
- session loading keeps the previous transcript until the new data
  arrives, aborts the request it replaced, ignores stale responses and
  surfaces a retryable error banner;
- search-jump pagination no longer pages through the previous session's
  history;
- REST calls get a 30 s timeout and caller abort support;
- WS queue overflow rejects the message and marks the bubble "not sent"
  instead of silently dropping the oldest;
- tool card bodies mount on first open (a 38-card session drops ~1 MB of
  markup and ~25k elements);
- identical /sessions requests coalesce, the streaming watch is a cheap
  signature, the content-tool key is one store computed, useTime shares
  one 30 s ticker, connect() clears the retry timer.

e2e opens result cards explicitly now that bodies are lazy.

webclient: reach the socket from cards, and draw the proposal card with the kit ...

The skill-proposal card sent its decision through inject('wsSend'), but no
ancestor ever provided it — the click went nowhere and the card reported
"No connection". Form.vue carried the same latent bug since 9dfdb48.

- wsBridge.js: a module-level bridge. useWebSocket registers its send on
  setup and clears it on unmount; cards call wsSend() and get false back
  instead of silently dropping the payload.
- Form.vue uses the bridge and reports a refused send without marking the
  form submitted.
- SkillProposal.vue is rebuilt on the kit (GnCard, GnAlert, GnChip, GnList,
  GnSteps, GnDescriptionList, GnLoader, GnButton) and exports `bare`, so
  UiComponentCard no longer wraps it in a second frame with a dev header.
- registry.js tracks bare components; UiComponentCard renders them as-is.