Add support for half-credit HASS-A classes

[hanahmed05]

Summary

This PR adds support for distinguishing half-credit HASS-A classes in Hydrant. Previously, these classes were displayed identically to full-credit HASS-A classes, which could mislead users when planning their schedules.

Changes

• Added is_half_class field to the RawClass TypeScript interface
• Extended override schema to support is_half_class
• Updated backend packaging logic (package.py) to mark all 21M.1* and 21M.4* classes as half-credit
• Updated frontend rendering to display "HASS-A (half)" for these classes

Testing

• Regenerated dataset using python scrapers/package.py
• Verified is_half_class appears in public/latest.json
• Ran frontend (npm run dev) and confirmed:
  • Half-credit classes display "HASS-A (half)"
  • Full-credit HASS-A classes remain unchanged
• Checked that search, scheduling, and other course displays are unaffected

[dtemkin1]

Would it be possible to generalize this a bit? eg rather than having is_half_class count exclusively for HASS-A, it would apply to any of the HASS attributes? Not sure if any HASS-H's or HASS-S's are like that, but can't hurt to account for them in advance methinks, what do you think @psvenk ?