fix: evict superseded ticket list responses

[tom-sapletta-com]

Summary

• include project identity in ticket-list response cache keys
• evict the older signature-specific body for the same logical query before caching the new version
• retain one 78 MB full-history body per query instead of up to four after successive ticket mutations

Validation

• pytest -q: 371 passed, 6 skipped
• targeted cache/index/API suite: 54 passed
• Ruff changed modules and git diff --check: pass
• production observation after PR fix: bound indexed full-history reads #25: indexed burst stayed below 287 MiB; follow-up addresses the remaining multi-version body retention

Planfile ticket: PLF-3777