meter/v1 + governance/v1: budget response fields and habit confidence hints

[haasonsaas]

Two contract additions that support this week's integration work:

meter/v1: IngestWideEventResponse gains budget_exceeded (bool) and budget_message (string) so callers learn immediately if a wide event pushed them over budget. Supports evalops/meter#46 and #49.

governance/v1: ActionEvaluation gains habit_confidence (float) and habit_observation_count (int32) so callers can surface trust trajectory to humans — "94% confidence, 2 more approvals until auto-approve." Links to the approvals auto-approve work (evalops/approvals#15, proto#56).

Both are additive wire-compatible changes. All bindings regenerated (Go, Python, TypeScript).

[cursor]

PR Summary

Low Risk
Additive protobuf contract changes only, but they affect multiple generated client SDKs and any callers that deserialize these responses.

Overview
Adds two wire-compatible protobuf fields to support richer client feedback.

meter.v1.IngestWideEventResponse now returns budget_exceeded and budget_message so ingest callers can immediately see whether the event pushed them over budget.

governance.v1.ActionEvaluation now includes habit_confidence and habit_observation_count to let clients surface approval-habit/trust trajectory hints. All Go/Python/TypeScript generated bindings are regenerated accordingly.

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