feat: add faculty profile editing functionality and UI components

[ishad05]

Allow faculty to edit their profile photo and name

Closes #44.

What this does

• Faculty can now change their profile photo and name from /faculty/settings
• Click the avatar to upload a new photo, hover and click the ✕ to remove it
• Click the pencil next to the name to edit first and last name inline, save with the check button
• Sidebar avatar and name update right away, no page reload needed
• Students are not touched, this is faculty only as the issue asked

Pattern

• Followed Frappe CRM's ProfileSettings.vue for the interaction (avatar as the upload button, pencil to edit name)
• Two changes from CRM on purpose:
  • CRM writes the User doctype from the client. CS17 Profile is System Manager only and some faculty don't have that role, so I added a whitelisted update_my_profile endpoint guarded by faculty membership instead
  • CRM uploads the avatar as a private file. I upload public, because this site's existing profile pictures are already public, and private avatars would 403 the day a student needs to see one

Changes

• api.py: new update_my_profile(first_name, last_name, profile_picture) endpoint
• www/dashboard.py and get_user_profile: also return first_name / last_name so the edit form can seed values
• useCurrentProfile: now a small store so a save updates the sidebar live
• New FacultyProfileCard.tsx, wired into FacultySettingsPage
• File uploads use the existing useFrappeFileUpload, Frappe's attach hook links the file to the profile

Tests

• faculty-profile.spec.ts: API level, name save and derived full name, set and clear photo, blank last name rejected
• faculty-profile-ui.spec.ts: real UI, rename persists across reload, photo upload and removal
• Full suite is 154 green, yarn build and tsc --noEmit clean