docs(adr): align ADR-046 proposal worker model with synchronous handlers

[ohdearquant]

Body:

• Problem: ADR-046 describes proposal workers and PackEventConsumer, while the shipped behavior uses synchronous handler invocation.
• Proposed fix: amend ADR-046 to describe synchronous handlers, or ship the event consumer worker model before treating the ADR as current.
• Acceptance criteria: proposal lifecycle docs match handler behavior; any worker model is either implemented and tested or deferred; event-consumer terminology no longer implies shipped behavior if absent.
• Affected crates/ADRs: docs/adr/ADR-046-event-sourced-proposals.md:1, crates/khive-pack-kg/tests/integration.rs:3807, /Users/lion/khive-work/shows/khive-improvement-survey/roadmap/e2/inventory_adr_feature_migration.md:33.

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Source: khive-improvement-survey show — proposed backlog (propose-only synthesis). Dedup: NEW.