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/cookbooks/create_config.md

@@ -0,0 +1,63 @@
+# Create Config
+
+Generate `sssf.config.yaml` — the agent roster for a target repo.
+
+## Generate it
+
+```bash
+uv run <skill>/scripts/make_config.py
+```
+
+`<skill>` is the directory this skill was installed into (e.g. `~/.agents/skills/sssf` or a repo's `.claude/skills/sssf`).
+
+Writes `adws/adw_sssf_config/sssf.config.yaml` — creating the directory if needed — with the starter agents (planner, builder, scout, reviewer, documenter) wired to the prompt files `/sssf install` stamped into `adws/adw_data/prompt_engineering/`. That path is the default every ADW and the justfile look for; `--config` overrides it. `make_config.py` refuses to overwrite an existing config unless you pass `--force`, so retuning an existing roster is a hand edit — see `update_config.md`.
+
+## The rule
+
+**One agent, one prompt, one purpose.** An entry defines who an agent *is*: its coding agent, model, thinking level, and exactly one system prompt plus one user prompt. How it gets *used* — the output type, a per-call user prompt override — lives at the ADW call site, never here.
+
+## Schema
+
+```yaml
+defaults:
+  coding_agent: pi                 # v1: pi only (claude_code is specced, stubbed until v2)
+  model: google/gemini-3.6-flash   # ALWAYS provider/model-id — a bare id is ambiguous
+  thinking: medium                 # off | minimal | low | medium | high | xhigh | max
+  harness_engineering: []          # pi extension names
+  data_dir: adws/adw_data          # runtime home: {data_dir}/sessions/{adw_id}/{agent_name}/
+
+observability:
+  db: adws/adw_data/sssf.db        # tracer writes here; the UI polls it
+  poll_ms: 500                     # visualizer live-poll cadence
+
+agents:
+  - name: planner                  # ADW scripts name agents, never models
+    coding_agent: pi
+    model: google/gemini-3.6-flash
+    thinking: high
+    color: "#a78bfa"               # optional hex — this agent's lane color in the visualizer
+    purpose: Turn a request into a plan the builder can implement without asking questions.
+    prompt_engineering:
+      system: adws/adw_data/prompt_engineering/planner/system.md
+      user: adws/adw_data/prompt_engineering/planner/user.md
+
+  - name: scout
+    thinking: high                 # unset keys fall through to defaults
+    purpose: Find and report where things live; change nothing.
+    prompt_engineering:
+      system: adws/adw_data/prompt_engineering/scout/system.md
+      user: adws/adw_data/prompt_engineering/scout/user.md
+    tools:                         # optional allowlist — omit the key entirely for all tools
+      - read
+      - bash
+```
+
+Every agent entry merges over `defaults`, so an entry only states what differs. Pi's builtin tools are `read`, `bash`, `edit`, `write` — a read-only recon agent gets `[read, bash]`; a builder omits `tools` altogether.
+
+## After generating
+
+1. Each agent needs its prompt pair to exist on disk: `adws/adw_data/prompt_engineering/{name}/system.md` and `user.md`. `agents.validate()` fails the run at startup if either is missing.
+2. Write `purpose` as one sentence and make the system prompt say the same thing — the two should not drift.
+3. Validate by running the smallest ADW that names your agents; a bad entry fails fast, before anything spawns.
+
+Full field-by-field spec, thinking-level mapping, and model resolution: `references/config.md`. Retuning an existing roster: `update_config.md`.