feat(api): add wake-triggered feed auto-refresh

[sommio]

Summary

Add same-process wake-triggered feed auto-refresh so stale feeds can be
refreshed after sleep or freeze without changing bootstrap ingestion
semantics.

What changed

• Adds FEED_AUTO_REFRESH_INTERVAL_HOURS with a 6 hour default and a
  new durable FeedAutoRefreshState record for the last successful wake
  refresh.
• Extends feed ingestion to return structured run results and enforce a
  per-feed retry cap for transient failures.
• Introduces FeedAutoRefreshService and its repository to detect
  resume-like wall-clock gaps, skip overlapping runs, and persist the
  success timestamp only after a successful refresh wave.
• Keeps bootstrap behavior unchanged and reuses the existing ingestion,
  content enrichment, and summary refresh pipeline for wake-triggered
  runs.
• Adds e2e coverage and updates API docs plus the example environment
  file.

flowchart TB
    Resume[Same-process resume] --> Gap{Gap > interval?}
    Gap -- no --> Skip[Skip refresh]
    Gap -- yes --> Run[Background refresh]
    Run --> Ingest[FeedIngestionService]
    Ingest --> Content[ArticleContentService]
    Ingest --> Summary[ArticleSummaryService]
    Run --> State{Any feed succeeded?}
    State -- yes --> Mark[Persist new success timestamp]
    State -- no --> Keep[Keep previous timestamp]

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Verification

• Repository typecheck passed during push.
• Added unit and e2e coverage for the new wake-refresh path.

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