Include non-timestamp run dirs in scan

[AlexanderOnischenko]

Motivation

• Filesystem scans ignored run directories that did not match the timestamp naming convention (e.g. run_old, run_new), causing auto-resolve and replay selection to find zero inspected runs and fail.
• Allowing non-timestamped run directories to be considered ensures runs created with non-timestamp names are discoverable and selection logic works correctly.

Description

• Stop filtering out non-timestamped directories in _iter_fs_run_dirs so all subdirectories (except reserved names cases and runs) are considered during the filesystem scan in src/fetchgraph/tracer/resolve.py.
• Preserve existing sorting via _run_dir_sort_key so timestamped runs remain ordered appropriately while still including other run directories.
• Change affects run discovery only; no other behavior or public APIs were modified.

Testing

• Ran pytest tests/test_tracer_auto_resolve.py tests/test_tracer_export_resolve_latest_with_replay_ignores_provider_specidx.py tests/test_tracer_export_resolve_prefers_run_with_replay.py and all tests passed.
• Test run summary: 13 passed (no failures).

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Codex Task