feat: implement mutation testing via cargo-mutants and improve test coverage (issue #483) #518

Job	Run time
Rustfmt	10s
Clippy	6m 40s
Unit Tests (contracts/insurance)	1m 4s
Unit Tests (contracts/fractional)	48s
Build WASM (contracts/fractional)	9m 2s
Build WASM (contracts/oracle)	8m 45s
Build WASM (contracts/analytics)	9m 0s
Build WASM (contracts/lending)	8m 55s
Unit Tests (contracts/analytics)	28s
Workspace Tests (std)	7m 18s
Security Audit	3m 4s
Unit Tests (contracts/oracle)	1m 3s
Unit Tests (contracts/lending)	1m 3s
Build WASM (contracts/insurance)	9m 0s
	1h 6m 20s

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