feat(feed): hand off legacy proactive facts

[kachofugetsu09]

Summary

• add a Feed-owned adapter that hands legacy Wake content into the ordinary Content source
• join each legacy event_id to the canonical Feed provider row and bind the target to its exact content_hash revision
• hand off pending consume/expire acknowledgements through one Feed provider ACK while retaining the original action
• retain target-owned ACK receipts after the bounded provider ACK cache expires
• pin CI to Core H2 exact bd5db8c2f9f857c7b5a6e44abfbaf14a2f5485ee

Ordering and replay

• plan and verify are read-only and require a checkpointed provider database
• target state commits before Core appends its lineage marker
• a crash after target commit reuses the exact Content or ACK receipt
• ACK replay does not extend or repeat the provider ACK
• configured relative provider database paths keep the original Feed data root

History and ownership

• Core owns only the generic handoff protocol and append-only lineage; it contains no Feed identities
• Feed owns provider joins, revision meaning, provider acknowledgement, and durable target receipts
• Content remains the only owner of migrated content submissions
• formal Feed evidence was read-only: the observed 15/16 pending rows joined the Feed provider database by event_id; no hua-home state was changed

Validation

• 50 tests passed, including 12 legacy handoff tests
• fixtures cover 15 real-shape rows, target-before-marker crash replay, revision drift, consume and expire ACKs, ACK retention expiry, and nested relative db_path
• Pyright: 0 errors and 0 warnings
• exact Plugin API v3 contract passed
• compileall and git diff --check passed
• exact head eec005f received independent Terra xhigh APPROVE

Recovery

Pre-implementation bundle: /mnt/data/coding/backups/feed-legacy-handoff-20260823/pre-implementation-4ea1e2a4804678a9084466eb3fc195f24d082390-v2.bundle

This stacked draft targets the head branch of Feed PR #5. It does not deploy or modify the formal hua-home workspace.

[kachofugetsu09]

本 PR 的 head commit 已是 master 的祖先：基础 Content source 由 #5 落地，后续 #7–#11 已在其上继续修正并合并。当前没有可再合并的新 commit，因此作为 superseded 关闭。