Add exception_classes field to genesis.js proposal output schema

In genesis.js PROPOSER_SYSTEM, add a new top-level field to the proposal JSON output schema (alongside existing fields like structural_veto, resolution_event, manual_entry_path): `"exception_classes": "<= 40 words: name 2-3 specific situations where this workflow must NOT fire autonomously or routes differently. Format: 'situation: routing'. Minimum: one exception for buyer tier, one for data-quality failure. Do not write 'the system handles exceptions'."`. Add a mandatory instruction above the schema definition: 'Exception classes are NOT optional. Every automated workflow has situations where it fails or should hand off. Name them before describing the happy path. A hypothesis with no named exception classes will score 0 on evaluation axis exception_class_named regardless of other merits. Pattern that passes: Enterprise accounts route to CSM; missing-artifact cases defer and notify; ambiguous resolution routes to human. Pattern that fails: The system will learn exception cases over time.'

After 2 genesis cycles (~62 new hypotheses at current 31/week throughput), at least 55% of generated proposals include a non-empty exception_classes field with ≥2 distinct named situations (not paraphrases). The companion exception_class_named axis (Proposal 1) will show mean score increase from ~0.1 to ≥1.2 on newly generated hypotheses within 2 weeks, measurable by comparing axis score distributions before/after.

After deploying the prompt change, manually inspect 10 genesis outputs from the next 2 cycles. If more than 4 of 10 contain only a single exception class, or if any contains only 'handled by the system' variants, the instruction is being satisfied with boilerplate. Secondary falsifier: if the mean exception_class_named axis score on new hypotheses does not exceed 0.8 within 2 weeks of both proposals being live, the genesis prompt change is not producing content the evaluator can score.

Deferred. Engine logic for this proposal is sound or partial, but the build was not prioritised this cycle.