chore: deduplicate gitignore entries #83

Job	Run time
TSan (Ubuntu)	3m 17s
Build & Test (ubuntu-24.04)	3m 25s
Server Codecs (Ubuntu)	4m 53s
Full Suite 394/394 (Ubuntu)	5m 5s
Build & Test (Windows / MSVC)	4m 19s
License Compliance	1m 38s
UBSan (Ubuntu)	2m 4s
Python SAST (bandit)	10s
Coverage (Ubuntu, Clang-18)	2m 47s
Post-Quantum PQ (Ubuntu)	9m 35s
Mutation Testing Baseline (Ubuntu)	2m 13s
ASan + UBSan (Ubuntu)	4m 15s
Benchmark Registry	4s
Build & Test (macos-14)	1m 53s
Fuzz (Ubuntu, Clang-18)	9m 58s
Secrets Scan (gitleaks)	5s
Benchmarks (Ubuntu)	2m 25s
	58m 6s

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