feat: Replace Meetings with Calendar - events with types and assigned users

- Rename meetings table to events with type field (meeting/event)
- Add eventUsers junction table for user assignments
- Members see only events they're assigned to
- Calendar endpoint returns events + todos for month
- Add migration SQL for database changes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/db/schema.js

@@ -242,11 +242,12 @@ export const timesheets = pgTable('timesheets', {
   updatedAt: timestamp('updated_at').defaultNow().notNull(),
 });
 
-// Meetings table - meetingy/stretnutia (iba admin môže CRUD)
-export const meetings = pgTable('meetings', {
+// Events table - udalosti v kalendári (meeting/event)
+export const events = pgTable('events', {
   id: uuid('id').primaryKey().defaultRandom(),
   title: text('title').notNull(),
   description: text('description'),
+  type: text('type').notNull().default('meeting'), // 'meeting' | 'event'
   start: timestamp('start', { withTimezone: true }).notNull(),
   end: timestamp('end', { withTimezone: true }).notNull(),
   createdBy: uuid('created_by').references(() => users.id, { onDelete: 'set null' }),
@@ -254,6 +255,16 @@ export const meetings = pgTable('meetings', {
   updatedAt: timestamp('updated_at', { withTimezone: true }).defaultNow().notNull(),
 });
 
+// Event Users - many-to-many medzi events a users (kto vidí udalosť)
+export const eventUsers = pgTable('event_users', {
+  id: uuid('id').primaryKey().defaultRandom(),
+  eventId: uuid('event_id').references(() => events.id, { onDelete: 'cascade' }).notNull(),
+  userId: uuid('user_id').references(() => users.id, { onDelete: 'cascade' }).notNull(),
+  assignedAt: timestamp('assigned_at').defaultNow().notNull(),
+}, (table) => ({
+  eventUserUnique: unique('event_user_unique').on(table.eventId, table.userId),
+}));
+
 // Time Entries table - sledovanie odpracovaného času používateľov
 export const timeEntries = pgTable('time_entries', {
   id: uuid('id').primaryKey().defaultRandom(),