Add September 21–22 FastPrep practice updates

[perixtar]

Summary

• synchronize 73 reviewed FastPrep coding routes: 56 additions and 17 freshness upserts
• retain the prior September 21 generated catalog and add the September 22 Amazon and Tekion results
• regenerate only the four owned catalog projections

September 22 increment

• six new routes: Amazon Edit Distance, Amazon Word Ladder, Amazon Allocate Minimum Pages, Amazon Longest Subarray With K Distinct, Tekion Largest Rectangle in Histogram, and Tekion Next Greater Elements
• two freshness upserts: Amazon Trapping Rain Water and Amazon Rotting Oranges Variation
• no removals

Generated catalog

• 2,754 unique canonical routes
• Coding 2,221; SQL 38; System Design 358; Low-Level Design 94; AI Coding 43
• two generated pages; largest page 399,978 bytes
• changed files only: README.md, question-bank/page-2.md, formats/coding.md, and formats/coding-page-2.md

Verification

• python3 -m unittest discover -s scripts -p 'test_*.py' — 19/19 passed
• python3 scripts/sync-practice-formats.py --sync-date 2026-09-22 --check — passed
• git diff --check 501a8f337b0cb1fbb4394b1338aa71e7f3fc1b56...b22a2cad1ef9ddc9434ca047b612ab760ff746d9 — passed
• all eight September 22 FastPrep routes return HTTP 200
• route uniqueness, newest-first ordering, projection conservation, neutrality, and page-size audits passed

Independent review

• reviewed base: 501a8f337b0cb1fbb4394b1338aa71e7f3fc1b56
• reviewed head: b22a2cad1ef9ddc9434ca047b612ab760ff746d9
• full four-file diff and all 73 affected routes reviewed independently
• finding: the prior description still named the earlier head and counts; this description resolves it
• no P0, P1, or P3 findings; generated content passed
• remaining risk: 11 pre-existing legacy catalog-missing routes are outside this run's eight-route increment

This pull request remains draft. The automation is not authorized to change ready state or merge it.