Prove value: oracle sweep over new OSS repos + draft triage table #201

Agent brief — tier: mid (above-average). One PR (Closes #<this>); branch from main. House rules: AGENTS.md.

Goal

Per docs/notes/consolidation-and-positioning.md, "the actual priority" is proving value: run the differentiation oracle on more real OSS C# repos and widen the set of findings Own.NET catches that CodeQL / Infer# miss.

Sources of truth

• docs/notes/oracle.md — the method; docs/notes/oracle-known-fps.md — known FPs (do not re-report them as fresh).
• docs/notes/real-world-mining.md and docs/notes/mining.md — the write-up format and prior runs.
• docs/notes/field-notes-patterns.md — the pattern ledger to extend.
• Workflows mine.yml / oracle.yml, scripts/own-check.sh — the run surface (--severity warning is the oracle posture).

Deliverable

• Runs over 5–10 new OSS .NET repos (prefer WPF/WinForms/Avalonia + a couple of plain libraries for the clean-code control).
• A note under docs/notes/ with a findings table: repo / finding (code, location) / draft verdict (TP / FP / unsupported) / rationale / cross-tool coverage where cheap.
• New recurring shapes appended to field-notes-patterns.md; corpus reductions for clear TPs where feasible.

Guardrails — the triage boundary (important)

• Draft verdicts only for obvious cases. Anything borderline goes into an explicit "needs maintainer review" list with the evidence laid out — do not self-certify borderline TP/FP; final verdicts are reserved for the maintainer.
• Honest accounting: unsupported constructs and analyzer bails are counted, not hidden — a "clean" run that skipped half the files is reported as such.
• No analyzer code changes in this PR; precision gaps discovered here become their own issues (file them, one per pattern, linking the evidence).

Done when

The note + table are committed, ambiguous cases queued for review, new patterns ledgered, and any discovered precision gaps exist as linked follow-up issues.