fix(gateway): fix matrix lingering typing indicator

[asheriif]

What does this PR do?

Fixes the Matrix typing indicator lingering for ~30 seconds after Hermes has already sent a response.

Matrix typing events were sent with a 30000 ms timeout, but the Matrix adapter inherited the base stop_typing() no-op. As a result, cleanup calls after agent completion did not send a “typing stopped” event, so Matrix clients kept showing Hermes as typing until the timeout expired.

This PR adds a Matrix-specific stop_typing() implementation that calls set_typing(..., timeout=0), which mautrix sends as typing: false.

Testing

python -m pytest tests/gateway/test_matrix.py -q

Result:

112 passed in 1.57s

Related Issue

Fixes #6016

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)

Changes Made

• Add MatrixAdapter.stop_typing() to explicitly clear Matrix typing state.
• Add regression coverage asserting Matrix typing cleanup sends timeout=0.

How to Test

1. Receive a message from your agent on Matrix
2. Typing indicator is cleared once the message arrives

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform:

Documentation & Housekeeping

• I've updated relevant documentation (README, docs/, docstrings) — or N/A
• I've updated cli-config.yaml.example if I added/changed config keys — or N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — or N/A
• I've considered cross-platform impact (Windows, macOS) per the compatibility guide — or N/A
• I've updated tool descriptions/schemas if I changed tool behavior — or N/A