loops: mandate machine-docs/ for ALL coordination files (kickoff/prompts/plan/AGENTS)

Recent phases wrote STATUS/BACKLOG/REVIEW/JOURNAL to the repo ROOT because
build_kickoff + plan.md's tree used bare filenames, even though the loops'
AGENTS.md + INBOX/DECISIONS/DEFERRED conventions already said machine-docs/.
Make machine-docs/ the single mandated home everywhere: build_kickoff now
emits machine-docs/ paths + an explicit FILE-LOCATION RULE; both loop prompts
and plan.md (tree + seed step) updated; orchestrator AGENTS.md documents +
enforces it. resolve_state/INBOX handoff already read machine-docs/ first.

cc-ci-plan/plan.md

@@ -61,8 +61,9 @@ Do these in order. Each step is idempotent; re-running is safe.
    the server (`/etc/nixos` or existing flake), installed packages, whether Docker/Swarm/abra
    already exist, DNS that already points at the box. This is the rollback reference.
 
-4. **Seed the loop state files** (§7) if absent: `STATUS.md`, `BACKLOG.md`, `REVIEW.md`,
-   `JOURNAL.md`, `DECISIONS.md`. Give `BACKLOG.md` two H2 sections — `## Build backlog`
+4. **Seed the loop state files** (§7) if absent, ALL under `machine-docs/` (never the repo
+   root): `machine-docs/STATUS.md`, `machine-docs/BACKLOG.md`, `machine-docs/REVIEW.md`,
+   `machine-docs/JOURNAL.md`, `machine-docs/DECISIONS.md`. Give `BACKLOG.md` two H2 sections — `## Build backlog`
    (populated from §5 milestones) and `## Adversary findings` (empty) — per the single-writer
    rule in §6.1.
 
@@ -239,7 +240,10 @@ cc-ci/
 │   ├── architecture.md
 │   ├── runbook.md            # debugging failed runs
 │   └── baseline.md           # bootstrap snapshot
-├── STATUS.md  BACKLOG.md  REVIEW.md  JOURNAL.md  DECISIONS.md   # loop state (§7)
+├── machine-docs/             # ALL loop-state/coordination files live here (§7), NEVER repo root:
+│   │                         #   STATUS-*.md BACKLOG-*.md REVIEW-*.md JOURNAL-*.md (phase-namespaced)
+│   │                         #   DECISIONS.md DEFERRED.md ADVERSARY-INBOX.md BUILDER-INBOX.md
+│   └── ...
 └── .drone.yml                # pipeline for cc-ci's own repo (lint/self-test)
 ```