fix: Address review — remove stale Matrix references from runtime prompts

Critical fixes:
- vault/vault-agent.sh: Update comment and prompt to use PHASE:escalate
  instead of "send a Matrix message"
- dev/dev-agent.sh: Update escalation instruction from "reply via Matrix"
  to "respond via the forge"
- dev/phase-handler.sh: Update build_phase_protocol_prompt() escalation
  text from "reply via Matrix" to "respond via the forge"

Minor fixes:
- bin/disinto: Remove duplicate comment line in docker-compose header
- README.md: Update vault table row from "via Matrix" to "via vault/forge"
- BOOTSTRAP.md: Remove "Matrix credentials" from TOML description
- lib/AGENTS.md: Remove "callers may follow up via Matrix" from
  formula_phase_callback description

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

vault/vault-agent.sh

@@ -5,8 +5,8 @@
 # builds a prompt with action summaries, and lets the LLM decide routing.
 #
 # The LLM can call vault-fire.sh (auto-approve) or vault-reject.sh (reject)
-# directly. For escalations, it sends a Matrix message and marks the action
-# as "escalated" in pending/ so vault-poll skips it on future runs.
+# directly. For escalations, it writes a PHASE:escalate file and marks the
+# action as "escalated" in pending/ so vault-poll skips it on future runs.
 
 set -euo pipefail
 
@@ -76,7 +76,7 @@ For actions that need human approval (escalate), write a PHASE:escalate file
 to signal the unified escalation path:
   printf 'PHASE:escalate\nReason: vault procurement — %s\n' '<action summary>' \\
     > /tmp/vault-escalate-<action-id>.phase
-Then send a Matrix message with context about what needs approval."
+Then STOP and wait — a human will review via the forge."
 
 CLAUDE_OUTPUT=$(timeout "$CLAUDE_TIMEOUT" claude -p "$PROMPT" \
   --model sonnet \