fix(agents): scrub GRAPH_STATE* from adversary verification commands; raise review-suite max_agent_depth

FIX A: run_checks.py passed no env= to Popen, so verification commands
inherited the live GRAPH_STATE/GRAPH_STATE_FILE. Every suite script's
load_state() prefers GRAPH_STATE_FILE, so when the adversary reviews a repo
whose own tests exec these scripts (this repo's R5 tests) the leaked file
silently overrode the test state -> false failures. Popen now gets an env
with all GRAPH_STATE* keys removed. The five sibling script-test helpers
(review-gauntlet, code-reviewer, finding-verifier, step-runner,
deep-research) gain .env_remove("GRAPH_STATE_FILE") for hermeticity. New
R5 test loads state via GRAPH_STATE_FILE and asserts a shell-neutral
python3 -c probe sees both vars UNSET.

FIX B: the depth check compares the child's absolute depth against the
SPAWNER's own max_agent_depth (root = 0), so under
architect(0)->sisyphus(1)->review-gauntlet(2)->code-reviewer(3) the
code-review lane faulted "Max agent depth exceeded (4/3)". Limits are now
child depth + 1 headroom along the documented chains, with the chain in a
comment next to each key: code-reviewer 3->5, domain-reviewer 2->6,
architecture-reviewer 2->4, step-runner default->4 (explicit),
review-gauntlet stays 4. domain-reviewer's file-reviewer hop is documented
but inert (can_spawn_agents unset) - left unwired by decision; noted in
config and pinned via a DOCUMENTED_BUT_UNWIRED exemption in the new
bundled-config test, which pins every value and asserts per-hop headroom +
reachability along four chains.

assets/agents/domain-reviewer/config.yaml

@@ -23,7 +23,13 @@ enabled_skills:
 spawnable_agents:
   - file-reviewer
 max_concurrent_agents: 8
-max_agent_depth: 2
+# The limit is consulted by the SPAWNER against the child's absolute depth
+# (root = 0). Deepest documented chain: architect(0) → sisyphus(1) →
+# review-gauntlet | step-runner(2) → code-reviewer(3) → domain-reviewer(4) →
+# file-reviewer(5). This agent spawns depth-5 children; 6 = one level of headroom.
+# NOTE: can_spawn_agents is not yet set, so the file-reviewer hop is documented
+# but inert; 6 keeps the limit forward-compatible for when it is wired.
+max_agent_depth: 6
 
 variables:
   - name: project_dir