refactor(features): extract dice system to standalone module

Extract dice rolling functionality from modals.js into dedicated
feature module at src/systems/features/dice.js. This includes:
- rollDice() - core rolling logic with animation
- executeRollCommand() - dice notation parser
- updateDiceDisplay() - sidebar display updates
- clearDiceRoll() - clear last roll
- addDiceQuickReply() - quick reply integration

Also fixes ES6 module binding issue with pendingDiceRoll by adding
getPendingDiceRoll() getter function in state.js to ensure correct
value retrieval across module boundaries.

Reduces modals.js from 568 to 499 lines (-69 lines).
Creates dice.js with 113 lines of focused dice functionality.

src/systems/ui/modals.js

@@ -8,14 +8,20 @@ import {
     extensionSettings,
     lastGeneratedData,
     committedTrackerData,
-    pendingDiceRoll,
     $infoBoxContainer,
     $thoughtsContainer,
-    setPendingDiceRoll
+    setPendingDiceRoll,
+    getPendingDiceRoll
 } from '../../core/state.js';
 import { saveSettings, saveChatData } from '../../core/persistence.js';
 import { renderUserStats } from '../rendering/userStats.js';
 import { updateChatThoughts } from '../rendering/thoughts.js';
+import {
+    rollDice as rollDiceCore,
+    clearDiceRoll as clearDiceRollCore,
+    updateDiceDisplay as updateDiceDisplayCore,
+    addDiceQuickReply as addDiceQuickReplyCore
+} from '../features/dice.js';
 
 /**
  * Modern DiceModal ES6 Class
@@ -283,16 +289,17 @@ export function setupDiceRoller() {
 
     // Roll dice button
     $('#rpg-dice-roll-btn').on('click', async function() {
-        await rollDice();
+        await rollDiceCore(diceModal);
     });
 
     // Save roll button (closes popup and saves the roll)
     $('#rpg-dice-save-btn').on('click', function() {
         // Save the pending roll
-        if (pendingDiceRoll) {
-            extensionSettings.lastDiceRoll = pendingDiceRoll;
+        const roll = getPendingDiceRoll();
+        if (roll) {
+            extensionSettings.lastDiceRoll = roll;
             saveSettings();
-            updateDiceDisplay();
+            updateDiceDisplayCore();
             setPendingDiceRoll(null);
         }
         closeDicePopup();
@@ -301,14 +308,14 @@ export function setupDiceRoller() {
     // Reset on Enter key
     $('#rpg-dice-count, #rpg-dice-sides').on('keypress', function(e) {
         if (e.which === 13) {
-            rollDice();
+            rollDiceCore(diceModal);
         }
     });
 
     // Clear dice roll button
     $('#rpg-clear-dice').on('click', function(e) {
         e.stopPropagation(); // Prevent opening the dice popup
-        clearDiceRoll();
+        clearDiceRollCore();
     });
 
     return diceModal;
@@ -402,7 +409,7 @@ export function setupSettingsPopup() {
 
         // Re-render user stats and dice display
         renderUserStats();
-        updateDiceDisplay();
+        updateDiceDisplayCore();
         updateChatThoughts(); // Clear the thought bubble in chat
 
         // console.log('[RPG Companion] Chat cache cleared');
@@ -462,101 +469,26 @@ export function applyCustomThemeToPopup() {
 
 /**
  * Clears the last dice roll.
+ * Backwards compatible wrapper for dice module.
  */
 export function clearDiceRoll() {
-    extensionSettings.lastDiceRoll = null;
-    saveSettings();
-    updateDiceDisplay();
-}
-
-/**
- * Rolls the dice and displays result.
- * Refactored to use DiceModal class.
- */
-async function rollDice() {
-    if (!diceModal) return;
-
-    const count = parseInt(String($('#rpg-dice-count').val())) || 1;
-    const sides = parseInt(String($('#rpg-dice-sides').val())) || 20;
-
-    // Start rolling animation
-    diceModal.startRolling();
-
-    // Wait for animation (simulate rolling)
-    await new Promise(resolve => setTimeout(resolve, 1200));
-
-    // Execute /roll command
-    const rollCommand = `/roll ${count}d${sides}`;
-    const rollResult = await executeRollCommand(rollCommand);
-
-    // Parse result
-    const total = rollResult.total || 0;
-    const rolls = rollResult.rolls || [];
-
-    // Store result temporarily (not saved until "Save Roll" is clicked)
-    setPendingDiceRoll({
-        formula: `${count}d${sides}`,
-        total: total,
-        rolls: rolls,
-        timestamp: Date.now()
-    });
-
-    // Show result
-    diceModal.showResult(total, rolls);
-
-    // Don't update sidebar display yet - only update when user clicks "Save Roll"
-}
-
-/**
- * Executes a /roll command and returns the result.
- */
-async function executeRollCommand(command) {
-    try {
-        // Parse the dice notation (e.g., "2d20")
-        const match = command.match(/(\d+)d(\d+)/);
-        if (!match) {
-            return { total: 0, rolls: [] };
-        }
-
-        const count = parseInt(match[1]);
-        const sides = parseInt(match[2]);
-        const rolls = [];
-        let total = 0;
-
-        for (let i = 0; i < count; i++) {
-            const roll = Math.floor(Math.random() * sides) + 1;
-            rolls.push(roll);
-            total += roll;
-        }
-
-        return { total, rolls };
-    } catch (error) {
-        console.error('[RPG Companion] Error rolling dice:', error);
-        return { total: 0, rolls: [] };
-    }
+    clearDiceRollCore();
 }
 
 /**
  * Updates the dice display in the sidebar.
+ * Backwards compatible wrapper for dice module.
  */
 export function updateDiceDisplay() {
-    const lastRoll = extensionSettings.lastDiceRoll;
-    if (lastRoll) {
-        $('#rpg-last-roll-text').text(`Last Roll (${lastRoll.formula}): ${lastRoll.total}`);
-    } else {
-        $('#rpg-last-roll-text').text('Last Roll: None');
-    }
+    updateDiceDisplayCore();
 }
 
 /**
  * Adds the Roll Dice quick reply button.
+ * Backwards compatible wrapper for dice module.
  */
 export function addDiceQuickReply() {
-    // Create quick reply button if Quick Replies exist
-    if (window.quickReplyApi) {
-        // Quick Reply API integration would go here
-        // For now, the dice display in the sidebar serves as the button
-    }
+    addDiceQuickReplyCore();
 }
 
 /**