Remove exec agent — replaced by OpenClaw skill + vault API (#722)

## What

Removes the exec agent (PR #697). Its functionality is replaced by:

1. **OpenClaw skill** — teaches any OpenClaw instance to be the factory's face
2. **Vault API** — structured interface for proposals, approvals, rejections

The exec agent was rebuilding OpenClaw in bash. Every piece has a native OpenClaw equivalent:
- CHARACTER.md → SOUL.md
- exec/MEMORY.md → MEMORY.md
- exec-session.sh → session management
- exec-briefing.sh → heartbeats/cron
- Matrix dispatch → channel plugins

## Why

Prudence isn't a separate agent. She's what OpenClaw becomes when it has the disinto skill. One LLM, one vault API, no LLM-to-LLM.

## Related

- #721 — remove escalation, route through vault
- #709 — skill registry research
- #466 — example project (vault should have handled this, not escalation)

Co-authored-by: openhands <openhands@all-hands.dev>
Reviewed-on: https://codeberg.org/johba/disinto/pulls/722

bin/disinto

@@ -1486,27 +1486,6 @@ p.write_text(text)
   touch "${FACTORY_ROOT}/state/.reviewer-active"
   touch "${FACTORY_ROOT}/state/.gardener-active"
 
-  # Provision executive assistant compass (identity lives outside the repo)
-  local compass_dir="${HOME}/.disinto"
-  local compass_path="${compass_dir}/compass.md"
-  if [ ! -f "$compass_path" ]; then
-    mkdir -p "$compass_dir"
-    if curl -sf --max-time 10 "https://disinto.ai/compass.md" -o "$compass_path" 2>/dev/null; then
-      chmod 600 "$compass_path"
-      # Add EXEC_COMPASS to .env if not already present
-      if ! grep -q '^EXEC_COMPASS=' "$env_file" 2>/dev/null; then
-        printf 'EXEC_COMPASS=%s\n' "$compass_path" >> "$env_file"
-      fi
-      touch "${FACTORY_ROOT}/state/.exec-active"
-    fi
-  else
-    # Compass already exists — just ensure exec is active and env is set
-    if ! grep -q '^EXEC_COMPASS=' "$env_file" 2>/dev/null; then
-      printf 'EXEC_COMPASS=%s\n' "$compass_path" >> "$env_file"
-    fi
-    touch "${FACTORY_ROOT}/state/.exec-active"
-  fi
-
   echo ""
   echo "Done. Project ${project_name} is ready."
   echo "  Config:  ${toml_path}"