feat(#221): wire tagOp URL param from server to SearchFilterBar

Reads ?tagOp=OR from URL in +page.server.ts, passes it to the backend
search endpoint, and surfaces it via the filters return. +page.svelte
initialises tagOperator state from filters, writes it back to the URL
in triggerSearch(), and binds it to SearchFilterBar.

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

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

@@ -29,6 +29,7 @@ export async function load({ url, fetch }) {
 		? (rawDir as ValidDir)
 		: 'desc';
 	const tagQ = url.searchParams.get('tagQ') || '';
+	const tagOp = url.searchParams.get('tagOp') === 'OR' ? 'OR' : 'AND';
 
 	const isDashboard = !q && !from && !to && !senderId && !receiverId && !tags.length && !tagQ;
 
@@ -48,6 +49,7 @@ export async function load({ url, fetch }) {
 								receiverId: receiverId || undefined,
 								tag: tags.length ? tags : undefined,
 								tagQ: tagQ || undefined,
+								tagOp: tagOp === 'OR' ? 'OR' : undefined,
 								sort,
 								dir: dir || undefined
 							}
@@ -147,7 +149,7 @@ export async function load({ url, fetch }) {
 				senderName: senderObj?.displayName ?? '',
 				receiverName: receiverObj?.displayName ?? ''
 			},
-			filters: { q, from, to, senderId, receiverId, tags, sort, dir, tagQ },
+			filters: { q, from, to, senderId, receiverId, tags, sort, dir, tagQ, tagOp },
 			error: null as string | null
 		};
 	} catch (e) {
@@ -166,7 +168,7 @@ export async function load({ url, fetch }) {
 			readyDocs: [],
 			weeklyStats: null,
 			initialValues: { senderName: '', receiverName: '' },
-			filters: { q, from, to, senderId, receiverId, tags, sort, dir, tagQ },
+			filters: { q, from, to, senderId, receiverId, tags, sort, dir, tagQ, tagOp },
 			error: 'Daten konnten nicht geladen werden.' as string | null
 		};
 	}