Work Intent: preserve disk I/O counters from disks.ini

Work intent

Fix the array slot state parser so GraphQL ArrayDisk.numReads and numWrites preserve the non-zero counters already present in disks.ini instead of forcing both fields to 0.

Evidence

• api/src/store/state-parsers/slots.ts currently maps numErrors from the INI state but hard-codes numReads: 0 and numWrites: 0.
• api/dev/states/disks.ini contains non-zero read/write counters for active disks.
• The existing parser snapshot therefore asserts zeros even when its fixture contains non-zero counters.
• Downstream user report: https://github.com/dinglebear-ai/unraid/issues/396

Planned change

1. Add a regression assertion proving non-zero fixture counters survive parsing.
2. Map numReads and numWrites through the same numeric parser used by numErrors.
3. Update the existing parser snapshot and run the focused API test suite.

This is intentionally scoped to preserving the existing state-file data; it does not change the GraphQL schema or counter semantics.

Start in api/src/store/state-parsers/slots.ts and compare the disk counter mapping with numErrors. Use the non-zero values in api/dev/states/disks.ini to add a regression assertion, then update the existing parser snapshot and run the focused API test suite. Done means the parsed GraphQL counters retain the fixture values instead of becoming zero.