fix: Remove Matrix integration — notifications move to forge + OpenClaw (#732)

Remove all Matrix/Dendrite infrastructure:
- Delete lib/matrix_listener.sh (long-poll daemon), lib/matrix_listener.service
  (systemd unit), lib/hooks/on-stop-matrix.sh (response streaming hook)
- Remove matrix_send() and matrix_send_ctx() from lib/env.sh
- Remove MATRIX_HOMESERVER auto-detection, MATRIX_THREAD_MAP from lib/env.sh
- Remove [matrix] section parsing from lib/load-project.sh
- Remove Matrix hook installation from lib/agent-session.sh
- Remove notify/notify_ctx helpers and Matrix thread tracking from
  dev/dev-agent.sh and action/action-agent.sh
- Remove all matrix_send calls from dev-poll.sh, phase-handler.sh,
  action-poll.sh, vault-poll.sh, vault-fire.sh, vault-reject.sh,
  review-poll.sh, review-pr.sh, supervisor-poll.sh, formula-session.sh
- Remove Matrix listener startup from docker/agents/entrypoint.sh
- Remove append_dendrite_compose() and setup_matrix() from bin/disinto
- Remove --matrix flag from disinto init
- Clean Matrix references from .env.example, projects/*.toml.example,
  formulas/*.toml, AGENTS.md, BOOTSTRAP.md, README.md, RESOURCES.md,
  PHASE-PROTOCOL.md, and all agent AGENTS.md/PROMPT.md files

Status visibility now via Codeberg PR/issue activity. Human interaction
via vault items through forge. Proactive alerts via OpenClaw heartbeats.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/load-project.sh

@@ -58,17 +58,6 @@ svc = cfg.get('services', {})
 if 'containers' in svc:
     emit('PROJECT_CONTAINERS', svc['containers'])
 
-# [matrix] section
-mx = cfg.get('matrix', {})
-if 'room_id' in mx:
-    emit('MATRIX_ROOM_ID', mx['room_id'])
-if 'bot_user' in mx:
-    emit('MATRIX_BOT_USER', mx['bot_user'])
-if 'token_env' in mx:
-    emit('MATRIX_TOKEN_ENV', mx['token_env'])
-if 'mention_user' in mx:
-    emit('MATRIX_MENTION_USER', mx['mention_user'])
-
 # [monitoring] section
 mon = cfg.get('monitoring', {})
 for key in ['check_prs', 'check_dev_agent', 'check_pipeline_stall']:
@@ -110,10 +99,4 @@ if [ -z "${PROJECT_REPO_ROOT:-}" ] && [ -n "${PROJECT_NAME:-}" ]; then
   export PROJECT_REPO_ROOT="/home/${USER}/${PROJECT_NAME}"
 fi
 
-# Resolve MATRIX_TOKEN from env var name (token_env points to an env var, not the token itself)
-if [ -n "${MATRIX_TOKEN_ENV:-}" ]; then
-  export MATRIX_TOKEN="${!MATRIX_TOKEN_ENV:-}"
-  unset MATRIX_TOKEN_ENV
-fi
-
 unset _PROJECT_TOML _PROJECT_VARS _key _val