security: fix vulnerabilities 1-7 from security audit

- Fix #1: Share handler IDOR - enforce owner check on share operations
- Fix #2: list_files_query IDOR - bind folder queries to authenticated user
- Fix #3: Dedup handler IDOR - restrict dedup operations to file owner
- Fix #4: Trash handler OptionalAuthUser - require full AuthUser
- Fix #5: Error info leakage - sanitize 500 error responses
- Fix #6: Chunked upload IDOR - bind upload sessions to user_id,
  add verify_session_owner() check on all session operations
- Fix #7: CSP unsafe-inline removal - migrate all inline scripts,
  styles and event handlers to external files, tighten CSP to
  script-src 'self'; style-src 'self'

New files:
  - static/js/core/theme-init.js (render-blocking theme init)
  - static/js/core/sw-register.js (service worker registration)
  - static/css/views/device-verify.css (extracted inline styles)
  - static/js/views/device-verify/device-verify.js (extracted inline script)

src/interfaces/middleware/auth.rs

@@ -24,6 +24,7 @@ pub struct CookieAuthenticated;
 pub struct AuthUser {
     pub id: String,
     pub username: String,
+    pub role: String,
 }
 
 /// Reusable extractor that gets the user_id of the authenticated user.
@@ -50,6 +51,7 @@ where
             .map(|cu| AuthUser {
                 id: cu.id.clone(),
                 username: cu.username.clone(),
+                role: cu.role.clone(),
             })
             .ok_or(AuthError::UserNotFound)
     }
@@ -108,6 +110,7 @@ where
             |cu| AuthUser {
                 id: cu.id.clone(),
                 username: cu.username.clone(),
+                role: cu.role.clone(),
             },
         )))
     }