fix(recovery): preserve partial component proof and full-year retry scope

[lamemustafa]

Context

PR #117 is intentionally narrowed to checkpoint-only completion recovery and deletes the durable completion-marker family. Late review found two separate pre-existing PR changes that must not be patched in that final deletion round.

Scope

• Preserve exact completed component evidence when explicit cancellation sees a mixed completed/unresolved selection; do not clear a proved component or replace it with cancellation.
• For a full-year multi-artifact target, retry every remaining required artifact (or validate merged progress against the original composite target) before the ledger can become downloadable.

Acceptance criteria

• Synthetic tests cover a mixed GSTR-2B cancellation where one exact component is complete and others are unresolved; completion evidence remains fail-closed and Start cannot repeat the proven component.
• Synthetic tests cover a full-year target with one staged component and two remaining components; the returned retry scope and terminal ledger state cannot complete until all required artifacts are staged or explicitly unavailable.
• No new durable marker family, broad permissions, portal automation, or raw portal/taxpayer data is introduced.

Verification

• Focused background tests for both regressions plus the standard Pack type, lint, formatting, build, package, and relevant authenticated QA gates.