fix: bind reviewed-page retries to saved draft

[jz-krono]

User workflow

A Dot presents a Markdown draft for owner review before saving it to a Space. When a save response is lost or the card reconnects, an unchanged review should recover the same saved page. If the title, content, or destination changes while the thread and tool-call ID stay the same, the card should identify the existing save and require a new review for the changed draft.

Change

• Persist the normalized original draft alongside each new reviewed-page receipt. Existing databases gain the new column on startup, and earlier receipts remain readable.
• Return the original review draft during receipt recovery, even when the saved page has since been edited.
• Accept identical retries and return HTTP 409 for changed drafts under an existing receipt. Preserve the current Space-access check.
• Reconcile the restored receipt with the card's displayed draft before showing it as approved or sending a continuation. Show a review conflict with a link to the previously saved page when they differ.
• Document the matching-retry behavior in the README.

Reproduction and verification

On the pinned base commit c2569bb6, saving draft A and then submitting draft B with the same thread and tool-call ID returned HTTP 201 with page A. With this change, the second request returns HTTP 409; the original page and receipt remain intact.

Regression coverage exercises identical retries, changed title/content/destination, title normalization, receipt recovery after page edits, Space revocation, database migration/restart, and client recovery before a decision. The existing page-review recovery tests continue to pass.

• Node 24.19.0, npm 11.9.0.
• Full Vitest suite: 35 files, 166 tests passed.
• npm run check-format, npm run lint, npm run typecheck, npm run build: passed.
• UI QA: reviewed the conflict-state rendering logic, native keyboard buttons, and narrow-screen wrapping styles. Interactive viewport QA is the next verification step.