fix: render known issue evidence correctly

[forthfate]

Summary

• hide known-issue evidence-only entries from improvement proposal cards and filters
• show per-item evaluation scores and retain them as effect scores
• use record-indexed IDs consistently for known unresolved issues
• exclude evidence-only entries from run summaries and improvement analytics

Verification

• .venv/bin/python -m pytest (191 passed)
• .venv/bin/ruff check orbit/ backend/ tests/
• pnpm --filter agent-improvement-console-ui run build
• verified a live 3001 run renders a proposal with title, Proposed status, and score 7.0

[insighta-cloud]

No issues found.