Add human-readable input helpers for resource values

[NavarrePratt]

Problem or motivation

Problem

The discovery API's capacity filters (min_available_cpu_millicores, min_available_memory_bytes) require raw integers, forcing users to do mental math or inline conversions:

towers = cwsandbox.list_towers(
    min_available_cpu_millicores=2000,       # 2 CPUs
    min_available_memory_bytes=4 * 1024**3,  # 4 GiB
)

We already have format_cpu and format_bytes for converting raw values into readable output, but there's no inverse path. Users have to convert back into primitives when constructing filter queries.

Proposed solution

Desired outcome

Make it easier to express resource requirements in human-readable terms when calling discovery functions. The current example script (examples/discover_infrastructure.py) has the same issue.

Alternatives considered

No response

Additional context

No response