fixes#17630
## Recursive Concept Cycle Detection
- Track (conceptId, typeId) pairs during matching to detect cycles
- Changed marker from IntSet to HashSet[ConceptTypePair]
- Removed unused depthCount field
- Added recursive concepts documentation to manual
- Added tests for recursive concepts, distinct chains, and co-dependent
concepts
## Fix Flaky `tasyncclosestall` Test
The macOS ARM64 CI jobs were failing due to a flaky async socket test
(unrelated to concepts).
The test only accepted `EBADF` as a valid error code when closing a
socket with pending writes. However, depending on timing, the kernel may
report `ECONNRESET` or `EPIPE` instead:
- **EBADF**: Socket was closed locally before kernel detected remote
state
- **ECONNRESET**: Remote peer sent RST packet (detected first)
- **EPIPE**: Socket is no longer connected (broken pipe)
All three are valid disconnection errors. The fix accepts any of them,
making the test reliable across platforms.
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Co-authored-by: Andreas Rumpf <araq4k@proton.me>
1324183c38