refactor(skills): make skills portable across users/locations via workspace-relative paths + env var overrides

Changes:
- skills/lib.sh:
  - HOME_DIR default changed from $HOME to <workspace_root> (workspace self-sufficient)
  - Added CLAUDE_PROJECT_DIR / LOCAL_BIN env var pattern (default $HOME, overridable)
- skills/tmux-agent-orchestrate-monitor/scripts/reconcile.sh:
  - STATE_DIR moved from $HOME/.cache/... to <workspace>/.cache/tmux-agent-orchestrate-monitor
- skills/tmux-agent-orchestrate-create/scripts/create_session.sh:
  - WRAPPER uses $LOCAL_BIN env var (default $HOME/.local/bin)
- 6 SKILL.md: examples and explanations updated to mention env var override capability

User/portability contract:
- Workspace-internal data: .hermes/ + .cache/ (moves with workspace)
- User/system data: $HOME/* (overridable via CLAUDE_PROJECT_DIR, LOCAL_BIN)
- All env vars follow: ${VAR:-default} pattern with documented defaults

Verified on isolated server -L agy-homeport-test (kill-server after):
- syntax check PASS
- E2E: defaults resolve to workspace-relative paths
- E2E: env var override correctly changes paths
- 0 leftover direct $HOME references in code
- Global skill non-interference verified
- Main isolated server -L multi-agent-canary untouched

skills/tmux-agent-orchestrate-status/SKILL.md

@@ -48,7 +48,7 @@ The script:
 3. For each row in `tmux_sessions[]`:
    - tmux alive? (via `tmux has-session -t <name>`)
    - pane cmd, cwd (via `tmux list-panes`)
-   - resume UUID on disk? (claude: `~/.claude/projects/<key>/<uuid>.jsonl`; agy: `~/.gemini/antigravity-cli/conversations/<uuid>.db`)
+   - resume UUID on disk? (claude: `$CLAUDE_PROJECT_DIR/<key>/<uuid>.jsonl` with default `~/.claude/projects/`; agy: `$HOME_DIR/.gemini/antigravity-cli/conversations/<uuid>.db` with default `~/.gemini/...`)
 4. For each tmux session matching `*-creator-*` not in YAML → flag as "unregistered"
 5. Prints a table (default) or JSON (with `--json`)