⚡ Bolt: Optimize FirstAidRepository Search Performance

[NITISH-R-G]

💡 What: Replaced List<Map<String, dynamic>> _corpusRows with a typed List<_FirstAidEntry> _corpusEntries that pre-computes .toLowerCase() values for search haystacks during initialization rather than on each keystroke/query.
🎯 Why: Autocomplete and token scoring were causing excessive string allocations (toLowerCase() inside nested loops) and map lookup overheads during high-frequency searches.
📊 Impact: Reduces O(Q*N) repeated string processing latency during first-aid suggestions and lookup rendering, avoiding redundant dynamic string allocations.
🔬 Measurement: Code verified syntactically using dart analyze and tested functional correctness via targeted test suite executions (orchestrator_test.dart, widget_test.dart).

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PR created automatically by Jules for task 14538360634257190755 started by @NITISH-R-G

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