#8363 test(knowledge): accept either ordered index in the scale window check and bound discussion case text

Summary

• scale.integration.ts: the reconciliation window-scan plan may walk the v2 index or the primary key (the fixture's single connector is nearly the whole table). The check now requires every index in the plan to be one of those two and at least one to be present, instead of v2 only, so it still rejects a plan that reads the connector through another index and sorts
• github.ts exports exceedsGitHubTextLimit (the same count and 256-character boundary as the inline check it replaces in searchGitHub), and scripts/test-search-discussions-live.ts rejects over-limit case queries while parsing, before any oracle request
• Responds to review threads on #8356

Type of Change

• Other: test and script hygiene

Testing

• An oversized case fails at parse time with no request made
• sim-search live suites (218 tests) and type-check pass

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)