S11 — Close out: register, status, epic closure (Epic #286) #295

Part of epic #286 · S11 · Waits for: S10

Background

Close the epic so the repository goes back to maintenance mode without leaving its own claims
behind.

The work

• Register: resolve C-99 with the release, tests and S8 evidence. C-100 stays open
  as awaiting (its precondition is an empirical comparison of cm vs pgm totals, outside
  this repo). Header counts; clusters.
• README §status and CLAUDE.md status: 3.0.0 published.
• Close Reconciliation cannot place country mass into an all-zero grid — 2.9–7.3% of fatality mass lost, measured on a real 1,024-draw forecast #283 with the S8 numbers.
• Check every acceptance criterion in epic Epic — Reconciliation places every country's mass: donor fill for empty-grid draws (3.0.0) #286; close the stories, the tracking issue
  and the epic.
• Leave the "noted, not worked here" items from the epic as notes. Don't open them.

Acceptance criteria

• Every epic acceptance criterion is checked with a link to its evidence.
• bash docs/validate_docs.sh passes.
• Register open entries all name an external precondition (CLAUDE.md maintenance mode).

Validation

bash docs/validate_docs.sh; issue links.