Tasks: the suite writes into the checked-in `.the-loop/` when run from the repo root

Phase 4 of 4. Each task names the acceptance criterion it satisfies and the testing-plan row that proves it. Ordered as the ticket asks: stop new debris, remove the old, then make the next instance loud. The guard is written first so it can fail on the unfixed tree.

[x] A0 — reproduce, and find the writer. Full suite from the root on main: the tracked record is rewritten. A sitecustomize tracer names every write under either .the-loop/ with its stack. AC: AC1 · Test: T15.
[x] A1 — the guard. cli/tests/conftest.py: the audit hook, the autouse _no_protected_state_writes fixture, and pytest_sessionfinish. Run before any fix: it fails four tests, seven cases. AC: AC4 · Test: T3.
[x] A2 — the four writers. _dispatcher's portable_dir; the restart test's eventlog.configure call, plus a non-empty-log assertion; the health test's config file and $THE_LOOP_CLI_CONFIG; probe_subscription / report_subscription / _subscription_lines take cli_config, and the doctor test asserts the cache location. Deps: A1 · AC: AC1, AC2, AC5 · Test: T1, T2, T5.
[x] A3 — the guard's own tests. cli/tests/test_state_isolation.py. Deps: A1 · AC: AC4 · Test: T4.
[x] B1 — remove the debris. git rm both files under .the-loop/portable/; reword .gitignore's cli/.the-loop/ comment. AC: AC3 · Test: T1.
[x] C1 — docs. docs/capabilities/testing-and-contracts.md gains the rule and a history row. docs/capabilities/channels.md records that the probe resolves names through the state-root cache, with a history row. Deps: A2 · Test: T6.
[x] D1 — evidence. verification.md, self-review.md, security-review.md, documentation.md, reviewer-briefing.md. Deps: A1–C1.