Add sssf skill, installable via the skills CLI

Port the sssf skill from ~/.agents/skills/sssf into this repo so it can be
distributed and installed with the skills CLI (skills add INDigitalStudio/skills
--skill sssf).

- Copy the skill (SKILL.md, cookbooks, references, scripts, templates, and the
  visualizer app source) into sssf/.
- Gitignore build/runtime artifacts: the visualizer's node_modules/ and dist/,
  Python bytecode, and the machine-specific repos.json.
- Make the skill location-independent: install.py now stamps the skill's real
  path into the stamped justfile's skill_dir (replacing the hardcoded
  ~/.agents/skills/sssf), so 'just obs' finds the visualizer wherever the CLI
  installed the skill.
- Update cookbooks to use <skill>/scripts/... instead of the hardcoded path,
  and document the skills CLI install command.
- Update the repo README with install instructions.

sssf/templates/adws/adw_modules/utils.py

@@ -0,0 +1,77 @@
+"""Small shared helpers. Anything bigger belongs in its own module."""
+
+from __future__ import annotations
+
+import os
+import secrets
+import subprocess
+from datetime import datetime, timezone
+from pathlib import Path
+
+from dotenv import load_dotenv
+
+load_dotenv()
+
+
+def operator_env() -> dict[str, str]:
+    """The engineer's own environment, as their shell would hand it over.
+
+    Agents and quality blocks are meant to see exactly what the operator sees:
+    their PATH, their toolchains, their globally installed packages. Copying
+    os.environ gets almost all the way there — but ADWs launch under `uv run`,
+    which prepends its ephemeral venv's bin to PATH and sets VIRTUAL_ENV. That
+    venv holds the ADW's OWN dependencies (pydantic, pyyaml), not the
+    operator's, so anything a subprocess resolves through it — `python3`,
+    `pip`, every globally pip-installed CLI — silently becomes the wrong one.
+
+    Stripping the venv restores parity: `python3` in an agent's bash is the
+    same `python3` the engineer gets in their terminal. The ADW's own imports
+    are unaffected; this env is only ever handed to child processes.
+    """
+    env = os.environ.copy()
+    venv = env.pop("VIRTUAL_ENV", "")
+    if not venv:
+        return env
+    venv_bin = str(Path(venv) / "bin")
+    parts = [p for p in env.get("PATH", "").split(os.pathsep) if p and p != venv_bin]
+    env["PATH"] = os.pathsep.join(parts)
+    return env
+
+
+def new_id(length: int = 8) -> str:
+    return secrets.token_hex(length // 2)
+
+
+def now_iso() -> str:
+    return datetime.now(timezone.utc).isoformat(timespec="milliseconds")
+
+
+def ensure_dir(path: str | Path) -> Path:
+    p = Path(path)
+    p.mkdir(parents=True, exist_ok=True)
+    return p
+
+
+def resolve_prompt(arg: str) -> str:
+    """CLI prompt arg: a file path resolves to its contents, else inline text."""
+    try:
+        p = Path(arg)
+        if p.is_file():
+            return p.read_text()
+    except OSError:
+        pass
+    return arg
+
+
+def engineer_name() -> str:
+    name = os.environ.get("ENGINEER_NAME", "").strip()
+    if name:
+        return name
+    try:
+        out = subprocess.run(["git", "config", "user.name"],
+                             capture_output=True, text=True, timeout=5)
+        if out.returncode == 0 and out.stdout.strip():
+            return out.stdout.strip()
+    except OSError:
+        pass
+    return os.environ.get("USER", "engineer")