iter disc.1: boss-only commits + main-as-quarantine (no branches in implement)

Two project-wide rules are now explicit across every skill:

1. Only the Boss commits. No skill agent (implementer,
   brainstormer, planner, debugger, fieldtester, docwriter,
   architect, bencher) runs `git commit`. Agents write their
   artefacts to the working tree as unstaged changes; the Boss
   inspects, decides commit shape, and commits.
2. main HEAD is sacrosanct. No actor runs `git reset` or
   `git revert` on main. Bad work stays in the working tree
   where it is still discardable via `git checkout -- <paths>`.

Implement loses the `iter/<iter_id>` branch mechanic entirely;
Phase 0 of the orchestrator-agent now does a clean-tree check
and refuses to start on a dirty tree. Per-task agent commits
are removed everywhere; reviewers operate against
`git diff HEAD` instead of `pre_task_sha..head_sha`.

Motivation: 2026-05-11 iter 23.4 stranded prep2/prep3 commits on
an iter-branch that never integrated to main, then a corrected
spec falsely claimed those commits had shipped. Branch-per-iter
+ manual-Boss-merge + iter-stacking made the strand structurally
possible. See docs/journals/2026-05-11-iter-disc.1.md for the
full per-task notes and motivation.

skills/debug/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: debug
-description: Use when a bug surfaces — failing test, segfault, wrong stdout, panic, or any observable misbehaviour. Bug fixes are RED-first TDD; no fix is attempted before the failing test is committed. Mandatory for any bug, including ones that look trivial.
+description: Use when a bug surfaces — failing test, segfault, wrong stdout, panic, or any observable misbehaviour. Bug fixes are RED-first TDD; no fix is attempted before the failing test exists in the working tree. Mandatory for any bug, including ones that look trivial.
 ---
 
 # debug — RED-first bug diagnoser
@@ -57,10 +57,17 @@ Dispatch `ailang-debugger` with:
 | `repro_known` | One-line repro if known, otherwise the agent finds one |
 | `recent_iter` | Iteration that last touched the suspected area (often `git log` tail) |
 
-The agent commits the RED test as `test: red for <symptom>` and reports
-the handoff carrier for `implement` mini-mode. The agent does NOT write
-the fix — splitting RED (this skill) and GREEN (`implement` mini-mode)
-across two dispatches keeps the diagnosis honest.
+The agent writes the RED test to the working tree (uncommitted) and
+reports the handoff carrier for `implement` mini-mode. The agent does
+NOT commit anything, and does NOT write the fix — splitting RED (this
+skill) and GREEN (`implement` mini-mode) across two dispatches keeps
+the diagnosis honest. The Boss decides whether to commit the RED test
+as a separate audit-trail commit before dispatching `implement` mini-
+mode, or to hand the dirty working tree directly to mini-mode (the
+mini-mode orchestrator's Phase-0 clean-tree check will refuse the
+latter — so for an audit-trail-preserving flow the Boss commits the
+RED test first; for a streamlined-fix flow the Boss commits the
+combined RED+GREEN at the end of mini-mode).
 
 ## Handoff Contract
 
@@ -82,7 +89,8 @@ scope for the bug-fix iteration and gets queued for a separate one.
   Common Rationalisations table, and the Red Flags list. The
   orchestrator does not execute these phases directly.
 - **Hand-off target:** `skills/implement/SKILL.md` — runs the GREEN
-  side after the RED test is committed.
+  side after the Boss has decided whether to commit the RED test
+  separately or as part of the final fix commit.
 - **Project source:** former CLAUDE.md "Bug fixes — TDD, always"
   section is now superseded by this file; CLAUDE.md keeps a one-line
   pointer.