Establish prompt engineering baseline with Gold Standard tests

- introduce Gold Standard evaluation corpus
- document decision taxonomy
- define prompt-engineering methodology
- add regression workflow
- establish Prompt Version 2 baseline
- validate decision_simple, decision_deferred and decision_none

tests/gold/evil_meeting/transcript.txt

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+Alex: Okay, quick pass on the portal rollout. Wait, before that, the French CSV export broke again.
+
+Bea: It did not break again. The old export failed. The new exporter was not running on that tenant.
+
+Chen: Sorry, when you say old export, do you mean the nightly job?
+
+Bea: Yes, the nightly CSV job. Not the API export.
+
+Alex: Fine. So fact: tenant FR-7 still used the nightly CSV job yesterday.
+
+Dana: I thought Omar owned that tenant.
+
+Bea: Omar is the customer contact, not a participant here and not the technical owner.
+
+Chen: The technical owner is still Platform, but nobody from Platform is in this call.
+
+Alex: Should we decide to migrate FR-7 today?
+
+Dana: I want to, but we do not know if the mapping table is clean.
+
+Bea: Also, I said last week we should migrate it. I am changing that. Do not migrate until the mapping table is checked.
+
+Chen: So no migration decision today?
+
+Alex: Correct, no migration decision today.
+
+Dana: But we can decide one thing: the portal rollout note will say FR-7 is excluded from Friday's batch.
+
+Bea: Agreed. Excluded from Friday's batch.
+
+Chen: Yes, put that in.
+
+Alex: Action item: Bea checks the FR-7 mapping table by Thursday morning.
+
+Bea: Yes, I will check it by Thursday morning.
+
+Dana: And I will message Omar after Bea is done.
+
+Alex: Hold on, after Bea is done is not a date.
+
+Dana: Fair. Then no task for me yet. I need Bea's result first.
+
+Chen: Technical note: the API export uses the v2 mapping table, the nightly CSV job uses the legacy table.
+
+Bea: Correct.
+
+Alex: Open question: can FR-7 use the v2 mapping without a customer-side field rename?
+
+Dana: Also, can Omar confirm their preferred launch window?
+
+Chen: Omar can answer that, but again he is not in this meeting.
+
+Alex: Good. Back to the portal rollout. Friday's batch still includes DE-2 and NL-4.
+
+Bea: Yes, those two are unchanged.
+
+Dana: I personally think excluding FR-7 makes the rollout look messy.
+
+Alex: Noted as Dana's view, not a decision.
+
+Chen: And please don't write that Platform approved anything. They are absent.