fix: member status visibility, team creation improvements, join approval flow

- Fix other members' status not visible due to users collection viewRule restriction
- Fix empty status treated as 'away' instead of 'idle' in membersByStatus
- Auto-set creator to 'in_team' status when creating team session
- Filter current user from idle members invite list
- Fix group store isGroupOwner using pb.authStore instead of localStorage
- Add nginx no-cache headers for index.html
- Add join_requests collection migration and join approval flow
- Update groups collection rules and add requireApproval field
- Add Memory types for Phase 2 planning

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/components/team/IdleMembersList.vue

@@ -2,6 +2,7 @@
 <script setup lang="ts">
 import { computed } from 'vue'
 import { useGroupStore } from '@/stores/group'
+import { useUserStore } from '@/stores/user'
 import type { UserStatus } from '@/types'
 import { sendInvitation } from '@/api/invitations'
 import { ElMessage } from 'element-plus'
@@ -15,9 +16,10 @@ const props = withDefaults(defineProps<Props>(), {
 })
 
 const groupStore = useGroupStore()
+const userStore = useUserStore()
 
 const idleMembers = computed(() =>
-  groupStore.currentMembers.filter(m => m.status === props.status)
+  groupStore.currentMembers.filter(m => m.status === props.status && m.id !== userStore.userId)
 )
 
 async function inviteMember(userId: string, username: string) {