Curation v2 step 2: Claude Opus 5 editor, the Brief, per-provider budgets

- AnthropicBackend (Messages API, cached system block, output_config.effort,
  server-side fallbacks, refusal surfaced as an error); Llms { bulk, editor }
  with editor_or_bulk(); PriceTable-based UsageMeter per provider.
- [anthropic], [editorial], deepseek.max_concurrent_requests and
  curation.max_article_count config; startup logs resolved providers.
- Budget day is the UTC date of started_at, preloaded from
  runs.provider_costs_json; finish_run writes provider_costs_json and
  config_json. Stage A batches run concurrently with per-batch budget checks.
- Editor prompt with one-line "why" per pick; no minimum lineup size;
  --max-articles is a ceiling; top-up branch deleted; why stored on picks and
  issue_articles.why and rendered in chapters and In this issue.
- Summaries on the editor client (3k-token input, concurrency 4, bulk then
  excerpt fallback); "The Brief" replaces From the Editor; section intros gone.
- Colophon carries per-provider costs and models.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A1rCLQeKBgnBo3oTgHuTMe

examples/image_audit.rs

@@ -369,6 +369,7 @@ fn pick_for(target: &Target, content_html: String) -> Pick {
         section: target.issue.clone(),
         position: 0,
         is_lead: false,
+        why: None,
         summary: None,
         llm: None,
         discussion: None,
@@ -412,7 +413,6 @@ fn write_audit_epub(out_dir: &Path, picks: &[Pick], assets: &[ImageAsset]) {
                  Articles are re-extracted live; editorial, discussions and the \
                  world briefing are absent by design.</p>"
                 .into(),
-            section_intros: Default::default(),
             summaries: Default::default(),
         },
         world_briefing: None,