ci: auto-retry transient CI failures

[darach]

Adds retry workflow that re-runs only failed CI jobs, up to 2 retries.

[coveralls]

Pull Request Test Coverage Report for Build 21736722204

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.005%) to 79.789%

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Totals
Change from base Build 21736658352:	0.005%
Covered Lines:	34788
Relevant Lines:	43600

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💛 - Coveralls

[github-actions]

✅ Benchmark Results: No significant regressions

Click to expand benchmark comparison

group                                          main                                   pr
-----                                          ----                                   --
diff_patch_merge/crdt_lww/batch/100            1.00    127.4±2.12ns        ? ?/sec    1.16    147.8±1.51ns        ? ?/sec
diff_patch_merge/crdt_lww/single_comparison    1.00      0.6±0.00ns        ? ?/sec    2.50      1.6±0.00ns        ? ?/sec
format/toml/parsing/structural/large           1.41     32.0±0.32µs   443.7 MB/sec    1.00     22.7±0.15µs   626.0 MB/sec
gron_comparison/direct/large                   1.00    231.7±3.19µs   171.6 MB/sec    1.20    277.4±3.98µs   143.3 MB/sec
gron_comparison/direct/medium                  1.00     29.4±0.23µs   224.5 MB/sec    1.21     35.6±0.43µs   185.6 MB/sec
streaming/allocation/fresh_processor           1.00    325.7±5.17µs   354.1 MB/sec    1.16   376.4±11.23µs   306.4 MB/sec
streaming/chunk_throughput/chunk_size/1000     1.00      3.3±0.12ms   361.5 MB/sec    1.16      3.8±0.05ms   310.4 MB/sec
streaming/chunk_throughput/chunk_size/2000     1.00      3.3±0.05ms   366.2 MB/sec    1.22      4.0±0.03ms   300.8 MB/sec
streaming/chunk_throughput/chunk_size/500      1.00      3.3±0.03ms   359.3 MB/sec    1.18      3.9±0.03ms   305.0 MB/sec
streaming/jsonl_batch_size/optimized/10000     1.00      3.2±0.21ms   372.0 MB/sec    1.18      3.8±0.04ms   316.3 MB/sec

Threshold: 15% regression triggers warning

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Benchmarks compare this PR against main branch