fix(net): confirm block inventory activity after processing

[317787106]

What does this PR do?

A BLOCK INV currently refreshes peer activity before the block is validated. Record receipt-time eligibility and confirm that activity only after the matching block is successfully processed through the broadcast or sync path. Use the recorded receipt time and a monotonic updater; advertisers receive no block-provider contribution credit.

Keep pending receipts in a per-peer cache capped at 100 entries with one-minute expiration, clear it on disconnect, and coordinate registration and confirmation with one lock.

Why?

Unverified announcements should not keep a peer active, while honest advertisers should receive activity credit even when another peer supplies the block.

Split scope

Independent split 2 of #91, based directly on release_v4.8.3. Confirmation hooks use the release branch's existing successful-processing paths and check shutdown directly, so this PR does not depend on the provider-accounting PR (#97). After that PR merges, reconcile the overlapping handler hooks and use the monotonic updater for its new provider activity sites; inject a mock AdvService into the provider-accounting sync test fixture. Download scheduling and retry/recovery are separate changes.

Existing APIs remain available; added APIs are Java 8 compatible. No wire/storage formats, dependencies, or configuration change.

Validation

• ARM64/JDK 17: 51 focused and existing regression tests passed, including receipt eligibility, failure/shutdown, concurrent confirmation, cache limits/expiration, monotonic updates, and disconnect cleanup.
• checkstyleMain checkstyleTest passed.
• Semgrep: no findings in changed files.
• FindSecBugs: no new security findings versus the release base (36 existing logging warnings; the new mutable-cache getter is an expected internal API warning).
• Local integration rehearsal of all three splits: 159 networking tests and Checkstyle passed.
• Repository-wide test: 3,470 tests, 26 skipped, zero failures/errors.
• Local worktree commands skip :framework:generateGitProperties because the existing metadata plugin cannot resolve linked worktrees.

Related split PRs

• fix(net): validate block delivery before provider credit #97: block validation and provider accounting
• fix(net): confirm block inventory activity after processing #98: validated block inventory activity
• fix(net): separate block fetch eligibility and scheduling #99: block provider selection and scheduling

All three target release_v4.8.3 independently. The fourth retry/recovery PR will be proposed only after these three merge.