Expose persistent collection gaps and public Congress links

Retain bill and attachment failure reasons and derive retry counts from saved cursors. Show gap details and retry exhaustion in the collection console while preserving historical records and retry limits.

Convert Congress API bill links to public pages and cover diagnostics, mixed dated versions, persistent counts and legacy records with regression tests.

deploy/README.md

@@ -304,6 +304,13 @@ format is PNG, JPEG or GIF. They do not establish completeness or irrelevance.
 Relevant documents remain `partial`; documents whose relevance is still unknown
 are kept in bounded attachment retries rather than inserted as unrelated news.
 Congress meeting attachment failures retain the same retry evidence as articles.
+Bill and attachment retry records retain an optional `error` explaining missing
+dates, unavailable text formats or extraction failures. The console shows these
+reasons, original links, attempt counts and pending/exhausted state even while a
+new round runs. Historical records without a reason remain visible as such; this
+change neither resets their retry quota nor rewrites historical records.
+`unresolved_bills`, `bill_retry_pending` and `bill_retry_exhausted` are derived from
+the persisted bill retry cursor, independently of the latest round's statistics.
 The source API derives `attachment_gaps`, `attachment_retry_pending` and
 `attachment_retry_exhausted` from the persisted cursor, independently of the latest
 round's statistics. The console keeps these document counts visible across rounds;