feat(slack-bridge): collapse verbose Pinet output

[tmustier]

Summary

Refs #760.

Collapses verbose Pinet output surfaces so routine dispatcher/direct results stay compact by default while JSON/full details remain available when explicitly requested.

Included commits:

• d69c84d — collapse Pinet delivery cards
• 66ff8f2 — collapse direct Pinet tool result rendering
• f7acddf — compact direct Pinet result text so JSON/full outputs do not dump inline before renderer expansion

Validation

From the prior issue checkpoint:

• pnpm --filter @gugu910/pi-slack-bridge test -- pinet-tools.test.ts
• pnpm --filter @gugu910/pi-slack-bridge typecheck
• pnpm --filter @gugu910/pi-slack-bridge lint
• pnpm --filter @gugu910/pi-slack-bridge build
• Push pre-push hook on the main checkout also completed successfully:
  • pnpm lint
  • pnpm typecheck
  • pnpm test

Reload/cache caveat

The direct pinet(...) JSON/full output path is now compacted in the tool result text itself and remains expandable via the Pinet tool renderer.

A running Pi session must be loading this updated branch/package version for /reload to show the change. If the session is still loading the cached installed package under ~/.pi/agent/git/github.com/gugu91/extensions, update that cache or load the local checkout before reloading.

Related follow-ups

#762 and #763 track broader context/TUI policy beyond this issue's narrow Pinet output collapse fix.