feat: Profil-Kategorien + Begrüßung in Zielsprache

languages.greeting (de/en/sv geseedet), neue pair_categories-Tabelle
(abgeleitet aus statement- und objektverknüpften Wörtern via
word_categories) inkl. Backfill für bereits veröffentlichte Pairs.
derivePairCategories() wird beim Publish (pairs + pipeline) aufgerufen.
/auth/me liefert language_target_greeting, /auth/stats liefert
categories[] mit Punkten je Kategorie fürs Profil.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/db-migrate.js

@@ -331,6 +331,41 @@ async function migrate() {
     )
   `);
 
+  // M2M: pairs <-> categories — abgeleitet aus den verknüpften Wörtern (Statements + Objekte).
+  // Wird beim Publish materialisiert (src/lib/pairCategories.js). Basis für die Kategorie-Punkte im Profil.
+  await query(`
+    CREATE TABLE IF NOT EXISTS pair_categories (
+      pair_id     UUID NOT NULL REFERENCES pairs(id) ON DELETE CASCADE,
+      category_id UUID NOT NULL REFERENCES categories(id) ON DELETE CASCADE,
+      PRIMARY KEY (pair_id, category_id)
+    )
+  `);
+
+  // Backfill: Kategorien für bereits veröffentlichte Pairs ableiten. Idempotent (ON CONFLICT DO NOTHING),
+  // nach dem Erstlauf praktisch leer, da neue Pairs ihre Kategorien beim Publish selbst materialisieren.
+  await query(`
+    INSERT INTO pair_categories (pair_id, category_id)
+    SELECT DISTINCT pid, category_id FROM (
+      SELECT p.id AS pid, wc.category_id
+        FROM pairs p
+        JOIN (
+          SELECT statement_id, word_id FROM statement_positive_words
+          UNION
+          SELECT statement_id, word_id FROM statement_negative_words
+        ) sw ON sw.statement_id IN (p.positive_statement_id, p.negative_statement_id)
+        JOIN word_categories wc ON wc.word_id = sw.word_id
+       WHERE p.status = 'published'
+      UNION
+      SELECT op.pair_id AS pid, wc.category_id
+        FROM object_pairs op
+        JOIN pairs p2        ON p2.id = op.pair_id AND p2.status = 'published'
+        JOIN object_words ow ON ow.object_id = op.object_id
+        JOIN word_categories wc ON wc.word_id = ow.word_id
+    ) src
+    WHERE category_id IS NOT NULL
+    ON CONFLICT (pair_id, category_id) DO NOTHING
+  `).catch(() => {});
+
   // pairs.answer_type → single TEXT (was TEXT[], now back to single value + new 'question' type)
   await query(`ALTER TABLE pairs DROP CONSTRAINT IF EXISTS pairs_answer_type_check`).catch(() => {});
   await query(`
@@ -444,6 +479,9 @@ async function migrate() {
       FOR EACH ROW EXECUTE FUNCTION update_updated_at()
   `);
 
+  // Begrüßung pro Sprache (in der Sprache selbst, z. B. sv = "Hej") — für die persönliche Profil-Anrede
+  await query(`ALTER TABLE languages ADD COLUMN IF NOT EXISTS greeting TEXT`).catch(() => {});
+
   // user_names
   await query(`
     CREATE TABLE IF NOT EXISTS user_names (
@@ -489,12 +527,17 @@ async function migrate() {
   // Full unique constraint (not partial) so ON CONFLICT works cleanly
   await query(`CREATE UNIQUE INDEX IF NOT EXISTS languages_short_en_idx ON languages (short_en)`).catch(() => {});
   await query(`
-    INSERT INTO languages (short_en, titel_de, titel_en, titel_sv, status, published_at)
+    INSERT INTO languages (short_en, titel_de, titel_en, titel_sv, greeting, status, published_at)
     VALUES
-      ('en', 'Englisch',   'English', 'Engelska', 'published', NOW()),
-      ('sv', 'Schwedisch', 'Swedish', 'Svenska',  'published', NOW())
-    ON CONFLICT (short_en) DO UPDATE SET status = EXCLUDED.status, published_at = COALESCE(languages.published_at, EXCLUDED.published_at)
+      ('en', 'Englisch',   'English', 'Engelska', 'Hi',  'published', NOW()),
+      ('sv', 'Schwedisch', 'Swedish', 'Svenska',  'Hej', 'published', NOW())
+    ON CONFLICT (short_en) DO UPDATE SET
+      status       = EXCLUDED.status,
+      published_at = COALESCE(languages.published_at, EXCLUDED.published_at),
+      greeting     = COALESCE(languages.greeting, EXCLUDED.greeting)
   `).catch(() => {});
+  // Deutsch wird separat angelegt → Begrüßung nachtragen
+  await query(`UPDATE languages SET greeting = 'Hallo' WHERE short_en = 'de' AND greeting IS NULL`).catch(() => {});
 
   // Seed bbox for watermelon test object (only if bbox_x is still NULL)
   await query(`