Plant assistant: one agent management and operators can ask

New docs/plant-assistant.md (decision, Alexander, 26 Oct 2026): an
assistant for the whole plant, asked in Thai or English at kiosks, desks
and phones, answering from the knowledge base (SOPs as ERPNext Quality
Procedures, vendor manuals on the Assets, recipes and limits, this
repository, lessons learned) and from ERPNext and the machine-data store,
with sources on every answer. Roles and questions, what it does
(explain, trace, summarise, alert context, plan vs actual, drafts) and
never does (machines, submitting, safety improvisation, seeing more than
the asker, rating operators, needing the internet). Built on Typhoon 2.5
(open weights, Apache-2.0, CPU trial first), Typhoon ASR for optional
voice, pgvector retrieval, MCP tools in cnx-factory through the one
integration layer and the PostgreSQL replica; vinyl-ai GPU server only if
needed (~250k to 300k THB, RTX 5090 Thai retail Oct 2026). Test set per
role, phasing, cost, risks, open decisions.

Mirrors: digital-factory systems and machines tables, rough cost note;
catalogue advisor becomes a role of the assistant; worker-safety
training; roadmap item 18; README bullet and layout.

docs/worker-safety.md

@@ -7,7 +7,10 @@ commitments:
   maintenance staff, starting with the vendor-led commissioning training and
   extending into an ongoing in-house program. The pressing line combines
   hydraulics (~180 bar), saturated steam (10 bar / 180 °C), and hot PVC, and
-  every one of these demands trained, deliberate handling.
+  every one of these demands trained, deliberate handling. The
+  [plant assistant](plant-assistant.md) quotes the approved safety
+  procedures word for word and never improvises one; it supports this
+  training and does not replace it.
 - **Clean rooms for galvanics**: silvering and stamper electroforming will
   run in dedicated clean rooms with controlled access, proper ventilation and
   exhaust, and decontamination procedures for people and equipment leaving