probe-output.schema: the shared enums come from omx-contract's vocabulary (#115)

[linuxnow]

Closes #115.

The probe output keeps its own format and its own probe.* codes; the words it shares with the other readers of a measurement now come from omx-contract 2.18.0, declared once there.

What is derived now

• protocol/probe-output.schema.in names five enums as @OMX_<ITEM>@ tokens and holds no list of them: latency method (MEASUREMENT_LATENCY_METHODS: impulse-onset, declared-port, note-onset), the held notes' basis (MEASUREMENT_VOICE_BASES), machine.class.coreBand / clockBand (MACHINE_CORE_BANDS / MACHINE_CLOCK_BANDS) and offer.realtime (RESOURCE_THREAD_SCHEDULING).
• tools/protocol-gen writes each token from the item's _INIT in <omxcontract/omx_vocabulary.h>, in the contract's order, and does not build when a word list is not its _COUNT. The generated probe-output.schema.json has the same values as before (only the five lists are now written on one line).
• src/probe.c writes the bands, the latency method and the scheduling class by the header's names instead of literals; the documents it writes are unchanged.
• The probe.* outcomes, steps, limits, limit mechanisms, reasons and profile codes stay this protocol's own, as do cancelledBy, via and plugin.format.

Checks

• make test-vocabulary (new, in make test): tests/vocabulary_derived.py reads the installed omx-vocabulary.schema.json (pkg-config datadir of omx-contract, or OMX_VOCABULARY) and holds every enum the template takes by a token to $defs.<ITEM>.enum, word for word and in order; requires the five items above to be taken that way; refuses a template list that is a whole contract item typed by hand; and checks that note-onset is a latency method. A positive control tells a contract with a word more and one reordered apart.
• make test-contract gains a scratch omx_vocabulary.h with a latency method more: the schema the generator writes follows, and the same list without its count does not build.
• make check-generated keeps the generated schema current with the header.

Sabotages (make sabotage), each seen red:

• the generated schema lost a latency method the contract has
• the generated schema has the clock bands in an order of its own
• a copy of the contract gives its hosts a scheduling class the schema does not have
• the template types the latency methods by hand again
• the template takes the voice basis from nowhere
• the generator types the latency methods by hand
• the generator does not hold a word list to its count

Two existing sabotages had their text moved with the code (the note-onset schema entry, now on one line; the note-onset method in src/probe.c, now a macro).

Packaging: the floor of omx-contract-devel / libomx-contract-dev rises to 2.18.0, the first release with omx_vocabulary.h; both channels carry it. No version or changelog change.

Verified in the worker image with omx-contract-devel 2.18.0: make test green, make sabotage green but for "worker_env is not applied to a running worker", which survives on main as well when the suite runs niced (#103).

Codes: none. No hosting.* code is added, removed or renamed; the step's hostingCode stays a pattern.

[linuxnow]

Coordinator's answers (2026-10-20, recorded in decisions-2026-10-19.md): (1) limit.unit and cost.unit stay plugin-hostd's own lists, but add a check that every word is a word of the contract's RESOURCE_UNITS (a subset test), so they cannot drift to a word the core lacks; do it in this PR if small, else as a follow-up issue. (2) machine.class field names and machine.profile field names: derive them the same way (tokens from MACHINE_CLASS_FIELDS and MACHINE_PROFILE_FIELDS); a follow-up PR is fine, file the issue. (3) The packaging floor rises to omx-contract-devel >= 2.18.0 with this change: agreed, it is part of the change, not a spec change. The release 0.6.0 PR (#119) is merged and is not touched; this PR goes in the next plugin-hostd release. Image: the worker image needs a rebuild with contract 2.18.0 (ops#219); CI here installs the published 2.18.0.