Feat/notification center profile settings

[exronnin]

Closes #298
Closes #299

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Description

Adds richer user profile/settings management and upgrades the notifications center.

Changes

• Added editable profile fields for display name, bio, avatar, and privacy preferences.
• Added account-level notification/privacy controls in settings.
• Persisted profile preference fields through the user API and Prisma schema migration.
• Improved notifications page with pagination, refresh, loading/empty states, and deep-link navigation.
• Synced unread notification counts between the notifications page and navbar bell.
• Updated notification API responses to include unread counts after fetch/read actions.
• Added/updated API and notification tests.

Verification

• Notification tests pass with mock DB: 25 passed.
• Lint passes with only existing console warnings.
• Full tsc --noEmit still has pre-existing test typing failures unrelated to these commits.

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Checklist

• I have tested my changes locally
• I have updated documentation as needed
• I have run npx prisma generate after schema changes
• I have run npx prisma migrate dev or npx prisma migrate deploy as appropriate

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Post-Merge Steps for Maintainers

If this PR includes changes to the Prisma schema:

1. Run the following command to apply the migration to your database:

   npx prisma migrate deploy

   or, for local development:

   npx prisma migrate dev

2. Ensure your CI pipeline runs the migration before tests (add this step if missing):

   - name: Run Prisma Migrate
     run: npx prisma migrate deploy

3. Make sure the database user in CI has permission to run migrations.

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If you have any questions, please comment on this PR.

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