feat(localization): add difficult vocabulary marking features in multiple languages

- Introduced new localization strings for marking vocabulary as difficult, including options to save and remove difficult marks.
- Enhanced user experience by providing feedback on the status of difficult vocabulary in Cebuano, Spanish, and French.
- Updated existing localization files to ensure consistency across languages, supporting the recent vocabulary management features.

frontend/src/dialogues/socialnetwork/VocabPracticeDialog.vue

@@ -199,6 +199,9 @@ export default {
       locked: false,
       autoAdvanceTimer: null,
       hardVocabMap: {}, // { [normalizedPairKey]: { learning, reference, markedAt } }
+      hardPhaseActive: false,
+      hardMasteryByKey: {}, // { [hardKey]: consecutiveCorrect }
+      cycleAskedIds: [],
     };
   },
   computed: {
@@ -294,6 +297,17 @@ export default {
     isCurrentMarkedHard() {
       if (!this.current) return false;
       return Boolean(this.hardVocabMap[this.getHardKey(this.current)]);
+    },
+    hardPoolItems() {
+      if (!Array.isArray(this.pool) || this.pool.length === 0) return [];
+      return this.pool.filter((item) => Boolean(this.hardVocabMap[this.getHardKey(item)]));
+    },
+    hardRemainingCount() {
+      const requiredConsecutiveCorrect = 2;
+      return this.hardPoolItems.filter((item) => {
+        const key = this.getHardKey(item);
+        return (Number(this.hardMasteryByKey[key]) || 0) < requiredConsecutiveCorrect;
+      }).length;
     }
   },
   methods: {
@@ -341,6 +355,9 @@ export default {
           markedAt: new Date().toISOString()
         }
       };
+      if (this.hardMasteryByKey[key] == null) {
+        this.hardMasteryByKey[key] = 0;
+      }
       this.saveHardVocabMap();
     },
     unmarkCurrentAsHard() {
@@ -350,8 +367,33 @@ export default {
       const next = { ...this.hardVocabMap };
       delete next[key];
       this.hardVocabMap = next;
+      if (this.hardMasteryByKey[key] != null) {
+        const nextMastery = { ...this.hardMasteryByKey };
+        delete nextMastery[key];
+        this.hardMasteryByKey = nextMastery;
+      }
+      if (this.hardPhaseActive && this.hardRemainingCount <= 0) {
+        this.hardPhaseActive = false;
+      }
       this.saveHardVocabMap();
     },
+    addCurrentToCycle() {
+      if (!this.current?.id) return;
+      if (this.cycleAskedIds.includes(this.current.id)) return;
+      this.cycleAskedIds = [...this.cycleAskedIds, this.current.id];
+    },
+    maybeStartHardPhase() {
+      if (this.srsMode || this.hardPhaseActive) return;
+      if (!this.pool.length || !this.hardPoolItems.length) return;
+      if (this.cycleAskedIds.length < this.pool.length) return;
+      this.hardPhaseActive = true;
+    },
+    maybeFinishHardPhase() {
+      if (!this.hardPhaseActive) return;
+      if (this.hardRemainingCount > 0) return;
+      this.hardPhaseActive = false;
+      this.cycleAskedIds = [];
+    },
     getLocalDateKey() {
       const d = new Date();
       const y = d.getFullYear();
@@ -455,14 +497,17 @@ export default {
       this.pendingRetry = null;
       this.pool = [];
       this.hardVocabMap = {};
+      this.hardPhaseActive = false;
+      this.hardMasteryByKey = {};
+      this.cycleAskedIds = [];
       this.locked = false;
       this.resetQuestion();
       this.$refs.dialog.open();
       this.$nextTick(() => {
         document.addEventListener('keydown', this.handleKeyDown);
       });
-      this.reloadPool();
       this.loadHardVocabMap();
+      this.reloadPool();
     },
     close() {
       if (this.autoAdvanceTimer) {
@@ -736,6 +781,36 @@ export default {
         if (!nextId) return null;
         return items.find((it) => it.id === nextId) || null;
       }
+      if (this.hardPhaseActive) {
+        const requiredConsecutiveCorrect = 2;
+        const hardItems = this.hardPoolItems.filter((item) => {
+          const key = this.getHardKey(item);
+          return (Number(this.hardMasteryByKey[key]) || 0) < requiredConsecutiveCorrect;
+        });
+        if (hardItems.length === 0) {
+          this.hardPhaseActive = false;
+          return null;
+        }
+        const rankedHard = hardItems
+          .map((item) => {
+            const key = this.getHardKey(item);
+            const mastery = Number(this.hardMasteryByKey[key]) || 0;
+            const st = this.perId[item.id] || { c: 0, w: 0, streak: 0, lastAsked: 0 };
+            return {
+              item,
+              mastery,
+              wrong: Number(st.w) || 0,
+              attempts: (Number(st.c) || 0) + (Number(st.w) || 0),
+            };
+          })
+          .sort((a, b) => {
+            if (a.mastery !== b.mastery) return a.mastery - b.mastery;
+            if (a.wrong !== b.wrong) return b.wrong - a.wrong;
+            if (a.attempts !== b.attempts) return a.attempts - b.attempts;
+            return Math.random() - 0.5;
+          });
+        return rankedHard[0]?.item || hardItems[Math.floor(Math.random() * hardItems.length)];
+      }
       if (this.pendingRetry?.id) {
         const retryItem = items.find((it) => it.id === this.pendingRetry.id);
         if (retryItem) {
@@ -861,9 +936,23 @@ export default {
       if (isCorrect) {
         st.c += 1;
         st.streak = st.streak >= 0 ? st.streak + 1 : 1;
+        if (this.hardPhaseActive && this.current) {
+          const key = this.getHardKey(this.current);
+          this.hardMasteryByKey[key] = Math.max(0, Number(this.hardMasteryByKey[key]) || 0) + 1;
+          if ((Number(this.hardMasteryByKey[key]) || 0) >= 2 && this.hardVocabMap[key]) {
+            const next = { ...this.hardVocabMap };
+            delete next[key];
+            this.hardVocabMap = next;
+            this.saveHardVocabMap();
+          }
+        }
       } else {
         st.w += 1;
         st.streak = st.streak <= 0 ? st.streak - 1 : -1;
+        if (this.hardPhaseActive && this.current) {
+          const key = this.getHardKey(this.current);
+          this.hardMasteryByKey[key] = 0;
+        }
       }
       st.lastAsked = Date.now();
       this.perId[id] = st;
@@ -943,12 +1032,23 @@ export default {
         this.resetQuestion();
         return;
       }
+      if (this.current?.id) {
+        this.addCurrentToCycle();
+      }
+      this.maybeStartHardPhase();
+      this.maybeFinishHardPhase();
       const retryDirection = this.pendingRetry?.direction || null;
       this.resetQuestion();
       if (retryDirection) {
         this.direction = retryDirection;
       }
       this.current = this.pickNextItem();
+      if (!this.current) {
+        this.maybeFinishHardPhase();
+        if (!this.hardPhaseActive) {
+          this.current = this.pickNextItem();
+        }
+      }
       if (!this.current) return;
       const prompt = this.currentPrompt;
       this.acceptableAnswers = this.getAnswersForPrompt(prompt, this.direction);