feat(tot): Phase L-6 4-layer tests

[k-yoshimi]

Summary

Phase L-6 of the TOT module library work: 4-layer test suite mirroring eqlib / trlib L-6, adapted for the orchestrator (every parameter name carries an `:` namespace prefix because tot's parameter space is the union of eq / tr / fp / ti / wr / wrx).

• Layer 1 equivalence (`python/totlib/tests/test_equivalence.py`): `Tot()` replay vs `test_run/baselines/tot_*/metrics.json` at tol=1e-10. Triple-skip-gated on libtotapi.so / totlib importability / `TOT_RUN_OK=1` (tot_init / tot_run / tot_get_state / tot_finalize are L-3/L-4/L-5 stubs returning TOT_ERR_NOT_IMPL today; the gate flips the test on once L-6 fan-out lands).
• Layer 2 C ABI negative (`tot/tests/c_abi/test_negative.c` + `tot_api_check_all` Makefile target): pre-init NOT_IMPL, unknown-namespace / missing-prefix / empty-prefix / prefix-only rejection (TOT_ERR_INVALID), per-module unknown-bare reject for every prefix, double-finalize safety, post-finalize dispatcher invariance.
• Layer 4 sweep (`python/totlib/tests/test_sweep.py`): 3x3 `eq:RR` x `eq:BB` grid with a fresh `with Tot()` per sample (re-init fix from trlib PR feat(trlib): plot API + TOML config runner (reference) #83 / eqlib L-6); verifies nrmax / nsmax stay invariant across cells. Same `TOT_RUN_OK` gating as Layer 1.
• Fixtures (`python/totlib/tests/fixtures/{init,tot_demo2014_params,tot_ht6m_params}.py`): namespaced PARAMS (`eq:RR=8.5/0.65`, `tr:DT=0.0001`, `tr:KNAMEQ=eqdata-HT6M`, ...) replaying the standalone `tot_demo2014_short` and `tot_ht6m_short` namelists.
• CI wiring: 5 new `totlib_*` rows in `test_run/test_definitions.conf` (c_abi / wrapper / ffi / equivalence / sweep).

No edits to totlib core (`totlib.py` / `state.py` / `_ffi.py` / `errors.py`).

Test plan

• `PYTHONPATH=python python3 -m unittest discover python/totlib/tests -v` -> 47 tests, 24 skipped, 0 failed (pass-or-skip clean; Layer 1 + Layer 4 skipped because libtotapi.so is not built and TOT_RUN_OK is not set in this sandbox).
• `bash -n test_run/run_tests.sh` -> rc=0 (no syntax regressions from the conf append).
• `./test_run/run_tests.sh -l | grep totlib_` -> 5 rows visible.
• On a build host: `make -C tot libtotapi.so` followed by `make -C tot tot_api_check_all` -> negative driver runs.
• On a build host: once L-6 fan-out lands inside the .so, `TOT_RUN_OK=1 ./test_run/run_tests.sh totlib_equivalence totlib_sweep` -> Layer 1 + Layer 4 PASS.

---

Note

Low Risk
Low risk: changes are limited to new test/fixture code and build/test harness wiring, with no modifications to totlib runtime logic. Main risk is CI/build breakage if the new tot_api_check_all target or TOT_RUN_OK-gated tests are misconfigured.

Overview
Adds Phase L-6 test coverage for the tot orchestrator mirroring the per-module L-6 shape: Layer 1 equivalence (test_equivalence.py) that replays namespaced fixtures through Tot() and diffs TotState.to_dict() against test_run/baselines/*/metrics.json, and Layer 4 sweep (test_sweep.py) that runs a 3x3 eq:RR×eq:BB grid with a fresh Tot() per cell to smoke-test lifecycle stability.

Introduces namespaced parameter fixtures for tot_demo2014_short and tot_ht6m_short under totlib.tests.fixtures, plus a new Layer 2 C ABI negative driver (tot/tests/c_abi/test_negative.c) and a composite make -C tot tot_api_check_all target to run smoke/param/run_so/negative. Wires the new totlib_* jobs into test_run/test_definitions.conf, with Layer 1/4 gated behind TOT_RUN_OK=1 until tot_run/tot_get_state are implemented.

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[k-yoshimi]

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