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>

docs/PHASE-PROTOCOL.md

@@ -30,7 +30,7 @@ Claude writes exactly one of these lines to the phase file when a phase ends:
 |----------|---------|---------------------|
 | `PHASE:awaiting_ci` | PR pushed, waiting for CI to run | Poll CI; inject result when done |
 | `PHASE:awaiting_review` | CI passed, PR open, waiting for review | Wait for `review-poll` to inject feedback |
-| `PHASE:escalate` | Needs human input (any reason) | Send Matrix notification; session stays alive; 24h timeout → blocked |
+| `PHASE:escalate` | Needs human input (any reason) | Send vault/forge notification; session stays alive; 24h timeout → blocked |
 | `PHASE:done` | Work complete, PR merged | Verify merge, kill tmux session, clean up |
 | `PHASE:failed` | Unrecoverable failure | Escalate to gardener/supervisor |
 
@@ -77,9 +77,8 @@ PHASE:awaiting_review → wait for review-poll.sh to post review comment
                          on APPROVE         → inject "approved" into session
                          on timeout (3h)    → inject "no review, escalating"
 
-PHASE:escalate        → send Matrix notification with context (issue/PR link, reason)
+PHASE:escalate        → send vault/forge notification with context (issue/PR link, reason)
                          session stays alive waiting for human reply
-                         on reply   → matrix_listener.sh injects reply into tmux session
                          on timeout → 24h: label issue blocked, kill session
 
 PHASE:done            → verify PR merged on forge
@@ -118,7 +117,7 @@ signal to the phase file.
 - **Post-loop exit handler (`case $_MONITOR_LOOP_EXIT`):** Must include an
   `idle_prompt)` branch. Typical actions: log the event, clean up temp files,
   and (for agents that use escalation) write an escalation entry or notify via
-  Matrix. See `dev/dev-agent.sh`, `action/action-agent.sh`, and
+  vault/forge. See `dev/dev-agent.sh`, `action/action-agent.sh`, and
   `gardener/gardener-agent.sh` for reference implementations.
 
 ## Crash Recovery