feat: course color generation (#179)

* feat: course color generation

* feat: add proper TS for hex colors

* refactor: fix oklab and improve contrast ratios

* fix: update HexColor type

* refactor: update color switch point

* refactor: color-related functions and types

* fix: imports and TS issues

* fix: imports and TS issues

* chore: add no-restricted-syntax ForInStatement

* chore(docs): add jsdoc

---------

Co-authored-by: doprz <52579214+doprz@users.noreply.github.com>

src/pages/background/lib/deleteSchedule.ts

@@ -14,10 +14,10 @@ export default async function deleteSchedule(scheduleId: string): Promise<string
 
     const scheduleIndex = schedules.findIndex(schedule => schedule.id === scheduleId);
     if (scheduleIndex === -1) {
-        return `Schedule ${scheduleId} does not exist`;
+        throw new Error(`Schedule ${scheduleId} does not exist`);
     }
     if (scheduleIndex === activeIndex) {
-        return 'Cannot delete active schedule';
+        throw new Error('Cannot delete active schedule');
     }
 
     schedules.splice(scheduleIndex, 1);