Applied 4 LOW-severity improvements from /speckit.analyze:
1. Clarified PNR format in FR-005 (TEST-{6 chars} not just 6 chars)
2. Added explicit FR-015 coverage note in tasks.md Phase 3
3. Documented infinite inventory design decision in T020
4. Connected documentation tasks to SC-006/SC-007 objectives
All changes are documentation clarifications, no functional impact.
Analysis showed 100% requirement coverage with zero blocking issues.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
