⚡ Optimize evidence adequacy check regex performance

[joy7758]

💡 What: Extracted the runtime regex compilation (re.fullmatch) for checking digests and URIs inside _check_causal_binding_complete into two module-level constants, _DIGEST_PATTERN and _URI_PATTERN.
🎯 Why: To prevent recompiling (or relying heavily on Python's regex compilation caching) inside a repeatedly called verification function, improving execution efficiency across many iterations of validation tasks.
📊 Measured Improvement: We ran a microbenchmark performing _check_causal_binding_complete over 100,000 iterations. Both the baseline and the improvement finished in approximately ~0.067s on the environment. The primary reason a large delta wasn't visible on the micro-benchmark is because Python's built-in re._MAXCACHE cache handles dynamic re-compilation well for very short loop environments. Nevertheless, this remains a standard optimization which properly explicitly unloads compilation overhead from function execution path and removes dependencies on implicit module caches.

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PR created automatically by Jules for task 8334918839282616192 started by @joy7758

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