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/application/ports/inbound.rs

@@ -1,5 +1,7 @@
 use std::sync::Arc;
 
+use uuid::Uuid;
+
 use crate::application::dtos::folder_dto::{
     CreateFolderDto, FolderDto, MoveFolderDto, RenameFolderDto,
 };
@@ -20,7 +22,7 @@ pub trait FolderUseCase: Send + Sync + 'static {
     ///
     /// Returns `NotFound` if the folder does not exist **or** belongs to
     /// another user.  All user-facing handlers should use this method.
-    async fn get_folder_owned(&self, id: &str, caller_id: &str) -> Result<FolderDto, DomainError>;
+    async fn get_folder_owned(&self, id: &str, caller_id: Uuid) -> Result<FolderDto, DomainError>;
 
     /// Gets a folder by its path
     async fn get_folder_by_path(&self, path: &str) -> Result<FolderDto, DomainError>;
@@ -33,7 +35,7 @@ pub trait FolderUseCase: Send + Sync + 'static {
     async fn list_folders_for_owner(
         &self,
         parent_id: Option<&str>,
-        owner_id: &str,
+        owner_id: Uuid,
     ) -> Result<Vec<FolderDto>, DomainError>;
 
     /// Lists folders with pagination
@@ -47,7 +49,7 @@ pub trait FolderUseCase: Send + Sync + 'static {
     async fn list_folders_for_owner_paginated(
         &self,
         parent_id: Option<&str>,
-        owner_id: &str,
+        owner_id: Uuid,
         pagination: &crate::application::dtos::pagination::PaginationRequestDto,
     ) -> Result<crate::application::dtos::pagination::PaginatedResponseDto<FolderDto>, DomainError>;
 
@@ -56,7 +58,7 @@ pub trait FolderUseCase: Send + Sync + 'static {
         &self,
         id: &str,
         dto: RenameFolderDto,
-        caller_id: &str,
+        caller_id: Uuid,
     ) -> Result<FolderDto, DomainError>;
 
     /// Moves a folder to another parent (ownership verified against caller_id)
@@ -64,16 +66,16 @@ pub trait FolderUseCase: Send + Sync + 'static {
         &self,
         id: &str,
         dto: MoveFolderDto,
-        caller_id: &str,
+        caller_id: Uuid,
     ) -> Result<FolderDto, DomainError>;
 
     /// Deletes a folder (ownership verified against caller_id)
-    async fn delete_folder(&self, id: &str, caller_id: &str) -> Result<(), DomainError>;
+    async fn delete_folder(&self, id: &str, caller_id: Uuid) -> Result<(), DomainError>;
 
     /// Creates a root-level home folder for a user during registration.
     async fn create_home_folder(
         &self,
-        user_id: &str,
+        user_id: Uuid,
         name: String,
     ) -> Result<FolderDto, DomainError>;
 
@@ -103,7 +105,7 @@ pub trait SearchUseCase: Send + Sync + 'static {
     async fn search(
         &self,
         criteria: SearchCriteriaDto,
-        user_id: &str,
+        user_id: Uuid,
     ) -> Result<Arc<SearchResultsDto>, DomainError>;
 
     /// Returns quick suggestions for autocomplete (lightweight, fast).