[FastPrep] Sync September 12 coding questions

[perixtar]

Summary

• synchronize the 28 coding problems selected by the finalized September 12 FastPrep 1Point3Acres crawl
• add 23 previously absent routes and refresh 5 existing routes from the verified production catalog
• regenerate the question-bank and coding-format pagination, counts, company list, and freshness markers
• resolve the generated-file rebase conflicts by rebuilding from current master, not by hand-splicing either conflict side

Source ledger publication: https://github.com/perixtar/codestar/pull/2468

Scope

• README.md
• question-bank/page-2.md
• formats/coding.md
• formats/coding-page-2.md

The additional generated-file delta is deterministic pagination and freshness projection. No question route was removed. Semantic comparison found exactly 23 target additions and 5 target row updates, with no unexpected substantive row changes.

Verification

• fresh production fastprepoa/problem export captured 2026-09-14T16:45:26.166Z (3,579 documents)
• guarded source-ledger/catalog upsert verification: exact 28-route set, terminal production/search state, exact catalog document hashes, and no duplicate coding routes
• TZ=UTC python3 scripts/refresh-freshness.py
• python3 scripts/sync-practice-formats.py --sync-date 2026-09-14
• PYTHONDONTWRITEBYTECODE=1 python3 -m unittest discover -s scripts -p 'test_*.py' (19 passed)
• python3 scripts/sync-practice-formats.py --sync-date 2026-09-14 --check
• git diff --check origin/master...HEAD
• semantic row audit: 1,959 → 1,982 coding/SQL problem-route rows; 23 additions + 5 substantive updates; 0 removals; 0 unexpected additions/updates; every target appears once in each logical index (two canonical links per row)
• generated format counts: Coding 1,946; SQL 36; System design 321; Low-level design 84; AI coding 34
• largest generated question-bank page: 399,990 bytes (below the 500 KB hard limit)

Independent regression review

A full independent regression review passed with no P0–P2 findings against final HEAD 1001696d0870343f87ddc89573db6f9ae993e57a and latest base 5b447de7930e69eb88f16e15785c5c10baaea961. It reviewed the complete diff, all 28 live-catalog bindings, exact 23-add/5-update scope, route conservation and uniqueness, company-list changes, newest-first and relative ordering, pagination/navigation, format projections and counts, freshness consistency, page limits, tests, and final clean worktree. The reviewer also confirmed HEAD is a direct child of the latest base.

This PR intentionally remains a draft pending human merge authorization.