fix: validate -s/--start flag and error on unparseable values

[Sladuca]

Summary

The -s/--start flag silently accepted any string. When chrono-node couldn't parse the input, the argParser fell back to "NOW" with no error — the command would proceed as if -s hadn't been passed at all.

Added a strict argParser that calls logAndQuit with a clear message when the input can't be parsed as a date.

Before (bad input silently treated as NOW):

$ sf nodes create -n 1 -d "4h" -s "test minimal request" -p 24
ℹ Using start time: Today, 9:35am PDT
...

After:

$ sf nodes create -n 1 -d "4h" -s "test minimal request" -p 24
Invalid start time: "test minimal request". Use ISO 8601 format (e.g. '2024-01-15T10:00:00Z'), a relative time (e.g. '+1h'), or 'NOW'.

Valid inputs still work as expected:

$ sf nodes create -n 1 -d "1h" -s "+1h" -p 24
✔ Start time must be "NOW" or on an hour boundary. Choose a time: Today, 11am PDT
✔ Create 1 reserved node for ~$14.78/node/hr on richmond? Yes
✔ Successfully created 1 reserved node

🤖 Generated with Claude Code

[semanticdiff-com]

Review changes with  

Changed Files

File	Status
src/lib/nodes/utils.ts	0% smaller

[joshi4]

Thanks!