feat: add PDF annotation feature (#40)

Backend:
- Add ANNOTATE_ALL permission
- Add ANNOTATION_NOT_FOUND and ANNOTATION_OVERLAP error codes
- V10 migration: document_annotations table with page/rect/color/owner
- DocumentAnnotation entity, AnnotationRepository, CreateAnnotationDTO
- AnnotationService: overlap detection (rectangle intersection), ownership enforcement on delete
- AnnotationController: GET (authenticated), POST/DELETE (ANNOTATE_ALL)
- 15 new tests (AnnotationServiceTest, AnnotationControllerTest) — TDD red/green

Frontend:
- AnnotationLayer.svelte: pointer-event drawing, colored rect overlays, delete buttons
- PdfViewer.svelte: annotate toggle, color picker, loads/saves/deletes annotations via API
- Disabled annotate button with tooltip for users without ANNOTATE_ALL
- canAnnotate exposed from layout server, passed to PdfViewer
- errors.ts + de/en/es translations for new error codes
- 3 new unit tests for AnnotationLayer — TDD red/green

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/+layout.server.ts

@@ -1,11 +1,10 @@
 import type { LayoutServerLoad } from './$types';
 
 export const load: LayoutServerLoad = async ({ locals }) => {
+	const groups: { permissions: string[] }[] = locals.user?.groups ?? [];
 	return {
 		user: locals.user,
-		canWrite:
-			locals.user?.groups?.some((g: { permissions: string[] }) =>
-				g.permissions.includes('WRITE_ALL')
-			) ?? false
+		canWrite: groups.some((g) => g.permissions.includes('WRITE_ALL')),
+		canAnnotate: groups.some((g) => g.permissions.includes('ANNOTATE_ALL'))
 	};
 };

frontend/src/routes/admin/page.svelte.spec.ts

@@ -29,6 +29,7 @@ const makeUser = (overrides = {}) => ({
 const baseData = {
 	user: undefined,
 	canWrite: true,
+	canAnnotate: false,
 	users: [makeUser()],
 	groups: [makeGroup()],
 	tags: []

frontend/src/routes/admin/users/[id]/page.svelte.spec.ts

@@ -24,7 +24,13 @@ const makeUser = (overrides = {}) => ({
 	...overrides
 });
 
-const baseData = { user: undefined, canWrite: true, editUser: makeUser(), groups };
+const baseData = {
+	user: undefined,
+	canWrite: true,
+	canAnnotate: false,
+	editUser: makeUser(),
+	groups
+};
 
 afterEach(cleanup);
 

frontend/src/routes/admin/users/new/page.svelte.spec.ts

@@ -10,7 +10,7 @@ const groups = [
 	{ id: 'g2', name: 'Admins', permissions: ['ADMIN'] }
 ];
 
-const baseData = { user: undefined, canWrite: true, groups };
+const baseData = { user: undefined, canWrite: true, canAnnotate: false, groups };
 
 afterEach(cleanup);
 

frontend/src/routes/conversations/page.svelte.spec.ts

@@ -12,6 +12,7 @@ afterEach(cleanup);
 const baseData = {
 	user: undefined,
 	canWrite: true,
+	canAnnotate: false,
 	documents: [],
 	initialValues: { senderName: '', receiverName: '' },
 	filters: { senderId: '', receiverId: '', from: '', to: '', dir: 'DESC' as const }

frontend/src/routes/documents/[id]/+page.svelte

@@ -875,7 +875,7 @@ function versionLabel(v: VersionSummary, index: number): string {
 					<p class="font-sans text-sm tracking-wide uppercase">{m.doc_no_scan()}</p>
 				</div>
 			{:else if fileUrl && doc.contentType?.startsWith('application/pdf')}
-				<PdfViewer url={fileUrl} />
+				<PdfViewer url={fileUrl} documentId={doc.id} canAnnotate={data.canAnnotate} />
 			{:else if fileUrl}
 				<div class="flex h-full w-full items-center justify-center overflow-auto p-8">
 					<img

frontend/src/routes/documents/new/page.svelte.spec.ts

@@ -10,6 +10,7 @@ afterEach(cleanup);
 const baseData = {
 	user: undefined,
 	canWrite: true,
+	canAnnotate: false,
 	persons: [],
 	initialSenderId: '',
 	initialSenderName: '',

frontend/src/routes/layout.svelte.spec.ts

@@ -22,6 +22,7 @@ const makeData = (overrides = {}) => ({
 		createdAt: ''
 	},
 	canWrite: true,
+	canAnnotate: false,
 	...overrides
 });
 

frontend/src/routes/page.svelte.spec.ts

@@ -20,6 +20,7 @@ afterEach(cleanup);
 const emptyData = {
 	user: undefined,
 	canWrite: true,
+	canAnnotate: false,
 	filters: { q: '', from: '', to: '', senderId: '', receiverId: '', tags: [] },
 	documents: [],
 	initialValues: { senderName: '', receiverName: '' },

frontend/src/routes/persons/page.svelte.spec.ts

@@ -14,7 +14,7 @@ const makePerson = (overrides = {}) => ({
 	...overrides
 });
 
-const emptyData = { user: undefined, canWrite: true, q: '', persons: [] };
+const emptyData = { user: undefined, canWrite: true, canAnnotate: false, q: '', persons: [] };
 const dataWithPersons = { ...emptyData, persons: [makePerson()] };
 
 afterEach(cleanup);