cobolrt exit route: record which COBOL quirks fire in production so customers can safely simplify the Java #4716

Owner-approved (2026-10-08): offer customers an exit route instead of lock-in.

What. Optional, low-overhead telemetry in cobolrt that records which quirk paths, keyed by catalogue rule ID, actually execute. Examples: intermediate truncation changed a value; a non-digit was read; a binary item wrapped; low-values were compared.

From that, generate a per-program simplification report: places where the COBOL semantics never mattered in production and a runtime call can be replaced by plain Java (BigDecimal/int arithmetic, String compares). Each suggestion comes with the evidence behind it and a test to keep.

Acceptance.

• Telemetry off by default, with measured overhead when on.
• A report format.
• A worked example on one burned-estate program: a suggested simplification applied, still PROVED, and readability improved.
• Docs for customers.

Part of the cobolrt-as-a-product epic (linked from the epic). Owner-approved direction, 2026-10-08.

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