Submit Memory Proposals

Stage kernel-submitted session-memory proposals (CONTRACT SERVER §).

The all-tier "为当前对话生成记忆" button has omicos-core run the user's OWN active model over ONE conversation and POST the result here using the SAME process/user auth as PUT /api/memory. ALL-TIER: there is NO Pro gate (the button spends the user's own model/credits; only the nightly dream worker is Pro). The kernel has already dropped NOOPs and applied the anti-hallucination gate.

Body: {session_id, origin:"session", proposals:[{op, target_slug, proposed_title, proposed_body?, old_string?, new_string?, rationale, importance, provenance}]}. Each item is validated (op enum, slug regex, 64 KiB body cap); the WHOLE batch is rejected atomically on the first bad item. prev_hash is captured per target slug at insert time (optimistic concurrency on later approve). Rows land status='pending'. Returns {inserted: n, proposals:[...]}.