test: add deterministic PM2.5 recovery coverage

[zeon256]

Summary

• Add a controllable wall clock and scripted PM2.5 provider for deterministic pipeline timing, error, deduplication, and shutdown tests.
• Add a fake object sink that models lost acknowledgements and verifies JSONL crash replay keeps stable object identity.
• Align the bucket example and timing guide with its 15-minute poll/flush cadence.

Verification

• cargo test --all-features — 75 passed, 3 ignored
• cargo clippy --all-targets --all-features -- -D warnings