fix(edge): fix loop detector argument shift, infinite loops, and shadow mode suppression

[levleontiev]

Summary

This PR fixes several bugs in the loop detection logic of fairvisor/edge:

1. Argument Shift in rule_engine.lua: The _call wrapper expects (func, default_value, ...). It was called without a default_value, causing all arguments passed to build_fingerprint to be shifted by one (e.g., method received path). Fixed by adding 0 as the default value.
2. Infinite Loops in loop_detector.lua: Table clearing using while #t > 0 do t[#t] = nil end is unsafe in Lua for certain scenarios. Replaced with proper for loops.
3. Shadow Mode Suppression: Loop detection was rejecting requests even in shadow mode. Added _wrap_shadow call to ensure shadow policies only report but do not block loops.
4. Nil Pointer in _build_decision_from_loop: Added a safety check for loop_result.action to prevent crashes when the action is missing.
5. Undefined Variable: Fixed a bug where values was used instead of kv in _append_sorted_key_values.

Testing

• Verified with a reproduction script that path|method are correctly included in the fingerprint and shadow mode correctly suppresses the rejection.
• All 654 unit tests passed.