Clamp and validate numeric MCP inputs for limits and timeouts

[dejaguarkyng]

Numeric MCP arguments currently rely on loose casts and simple defaults. Add local validation for list_jobs limit and stream_job_logs timeout_seconds so invalid values cannot produce surprising API calls or timers.

Acceptance criteria:

• list_jobs limit accepts only finite positive numbers and clamps to the documented max of 100.
• stream_job_logs timeout_seconds accepts only finite positive numbers and clamps to 600 seconds.
• Invalid numeric inputs return clear MCP tool errors.
• Tests cover missing defaults, negative values, zero, NaN-like inputs, and values over the max.