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>

formulas/run-rent-a-human.toml

@@ -6,7 +6,7 @@
 #
 # Trigger: action issue created by planner or any formula.
 # The action-agent picks up the issue, executes these steps, writes a draft
-# to vault/outreach/{platform}/drafts/, notifies the human via Matrix,
+# to vault/outreach/{platform}/drafts/, notifies the human via the forge,
 # and closes the issue.
 #
 # YAML front matter in the dispatching action issue:
@@ -150,21 +150,17 @@ Write the drafted content to the outreach directory, commit, and push.
 
 [[steps]]
 id    = "notify-human"
-title = "Notify human via Matrix"
+title = "Notify human and create PR"
 needs = ["write-draft"]
 description = """
-Notify the human, create a PR, and hand off to the orchestrator for CI.
+Create a PR for the draft and hand off to the orchestrator for CI.
 
 1. Read saved state:
      DRAFT_FILE=$(cat /tmp/rent-a-human-path)
      DRAFT_TITLE=$(cat /tmp/rent-a-human-title)
      BRANCH=$(cat /tmp/rent-a-human-branch)
 
-2. Send the Matrix notification:
-     source "$FACTORY_ROOT/lib/env.sh"
-     matrix_send "rent-a-human" "New {{platform}} {{action_type}} draft ready: ${DRAFT_TITLE}"
-
-3. Create a PR for the draft:
+2. Create a PR for the draft:
      PR_RESPONSE=$(curl -sf -X POST \
        -H "Authorization: token ${FORGE_TOKEN}" \
        -H "Content-Type: application/json" \