perf: migrate all user/session/auth IDs from VARCHAR(36) to native UUID

- Schema: all ~15 VARCHAR(36) columns → UUID with DEFAULT gen_random_uuid()
- Domain entities: User, Session, DeviceCode, AppPassword, Share → id: Uuid
- DTOs: CurrentUser.id → Uuid (API boundary DTOs keep String for JSON)
- Auth middleware: parse JWT claims.sub (String) → Uuid at boundary
- All repository traits, port traits, service impls updated end-to-end
- Handlers: pass Uuid by value (Copy, 16 bytes) instead of String refs
- Settings chain: updated_by column → Uuid (was text, caused setup crash)
- Removed ~650 lines of String↔Uuid conversion boilerplate
- Eliminates per-request heap allocations for ID cloning
- 16-byte binary comparison vs 36-byte string comparison in all queries
- Native UUID indexing in PostgreSQL (btree on 16 bytes vs 36-char text)

85 files changed, 1090 insertions(+), 1739 deletions(-)

src/domain/repositories/calendar_repository.rs

@@ -21,20 +21,20 @@ pub trait CalendarRepository: Send + Sync + 'static {
     /// Lists all calendars for a specific user
     async fn list_calendars_by_owner(
         &self,
-        owner_id: &str,
+        owner_id: Uuid,
     ) -> CalendarRepositoryResult<Vec<Calendar>>;
 
     /// Finds a calendar by name and owner
     async fn find_calendar_by_name_and_owner(
         &self,
         name: &str,
-        owner_id: &str,
+        owner_id: Uuid,
     ) -> CalendarRepositoryResult<Calendar>;
 
     /// Lists calendars shared with a specific user
     async fn list_calendars_shared_with_user(
         &self,
-        user_id: &str,
+        user_id: Uuid,
     ) -> CalendarRepositoryResult<Vec<Calendar>>;
 
     /// List public calendars
@@ -48,7 +48,7 @@ pub trait CalendarRepository: Send + Sync + 'static {
     async fn user_has_calendar_access(
         &self,
         calendar_id: &Uuid,
-        user_id: &str,
+        user_id: Uuid,
     ) -> CalendarRepositoryResult<bool>;
 
     /// Gets a custom property for a calendar
@@ -83,7 +83,7 @@ pub trait CalendarRepository: Send + Sync + 'static {
     async fn share_calendar(
         &self,
         calendar_id: &Uuid,
-        user_id: &str,
+        user_id: Uuid,
         access_level: &str,
     ) -> CalendarRepositoryResult<()>;
 
@@ -91,7 +91,7 @@ pub trait CalendarRepository: Send + Sync + 'static {
     async fn remove_calendar_sharing(
         &self,
         calendar_id: &Uuid,
-        user_id: &str,
+        user_id: Uuid,
     ) -> CalendarRepositoryResult<()>;
 
     /// Get calendar sharing information (who has access to this calendar)