docs(examples): add a Builder/Adversary loop-pair example (the cc-ci pattern)

A self-contained examples/builder-adversary/ that distills the cc-ci production
loop pair into a tiny, fully-local task (build a `wc` CLI in two phases):

- agents.toml: builder + adversary loops, persistent orchestrator, on_complete
  reporter, cleanlogs service; phase machine with a per-phase model override
- prompts/: kickoff template + builder/adversary roles carrying the load-bearing
  protocol (claim()/review() handoff, machine-docs file-location rule,
  WHAT+HOW+EXPECTED+WHERE=STATUS / WHY=JOURNAL anti-anchoring, WAITING-UNTIL liveness)
- plans/: two phase plans (wc, json) each with a cold-verifiable Definition of Done
- README: how to run, the work-repo two-clone isolation model, how to adapt

Verified: `agents.py status --config agents.toml` parses and lists all agents.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

examples/builder-adversary/plans/json.md

@@ -0,0 +1,32 @@
+# Phase `json` — machine-readable output
+
+**Mission.** Extend the `wc.py` from the previous phase with a `--json` mode, without regressing any
+`wc`-phase behaviour. Single source of truth for this phase.
+
+(The phase config gives the Builder `claude-opus-4-8` for this phase — an example of a per-phase
+model override; the Adversary stays on the default model.)
+
+## Definition of Done
+
+- **D1 — json output.** `python wc.py --json FILE` prints a single JSON object:
+  `{"lines": N, "words": N, "chars": N, "file": "FILE"}` (valid JSON, parseable by `json.loads`).
+  With stdin (no FILE), `"file"` is `null`.
+- **D2 — composes with flags.** `--json` honours `-l/-w/-c`: only the requested counts appear as keys
+  (plus `file`). E.g. `wc.py --json -l FILE` → `{"lines": N, "file": "FILE"}`.
+- **D3 — no regression.** Every `wc`-phase gate (D1–D4 there) still passes unchanged.
+- **D4 — tests green.** `test_wc.py` is extended for the JSON cases and `pytest -q` is all-green.
+
+## How the Adversary verifies (cold)
+
+```bash
+pytest -q                                              # D4 + D3 regression
+printf 'a b c\nd e\n' > /tmp/f.txt
+python wc.py --json /tmp/f.txt | python -c 'import sys,json; d=json.load(sys.stdin); \
+  assert d=={"lines":2,"words":5,"chars":10,"file":"/tmp/f.txt"}, d; print("ok")'   # D1
+python wc.py --json -l /tmp/f.txt                      # D2: expect {"lines": 2, "file": "/tmp/f.txt"}
+```
+
+The Builder restates the exact commands, expected JSON, and commit sha in
+`machine-docs/STATUS-json.md`. When every DoD item has a fresh PASS in `machine-docs/REVIEW-json.md`
+and there is no `## VETO`, the Builder writes `## DONE` to `STATUS-json.md` — this is the last phase,
+so the watchdog then fires the one-shot `reporter` (see `agents.toml` `[loop].on_complete`).