refactor: extract inline HTML to templates, split oversized files, fix bugs

- Extract all inline HTML from JS into 21 Handlebars templates (chat/, dialogs/, ui/)
- Split utils.mjs (1507) into barrel + helpers.mjs, combat.mjs, d30.mjs
- Split roll.mjs (1632) into barrel + roll-base.mjs, roll-prompt.mjs, roll-combat.mjs, roll-damage.mjs
- Split lethal-fantasy.mjs (1426) into bootstrap + chat-reaction.mjs
- Fix: missing async on injectDiceTray (free-roll.mjs:29 SyntaxError)
- Fix: weapon._id fallback for deserialized chat-message weapon objects
- Fix: missing await on rollModifier.evaluate() calls in roll-combat.mjs
- Fix: choices→choicesList ReferenceError in utils.mjs
- Fix: add 12 missing i18n keys (chooseWeapon, chooseSave, attackRoll, etc.)
- Fix: restore sideLabel in bonus-die-select.hbs
- Clean: remove dead messageContent param, console.log→log()
- Style: barrel files preserve existing import paths

templates/chat/_dice-breakdown.hbs

@@ -0,0 +1,14 @@
+<div class="dice-breakdown">
+  {{#each diceResults}}
+  <span class="dice-item">
+    <span class="dice-type">{{this.dice}}</span>
+    <span class="dice-separator">→</span>
+    <span class="dice-value">{{this.value}}</span>
+  </span>
+  {{/each}}
+</div>
+{{#if D30message}}
+<div class="d30-result">
+  <span class="d30-value">D30 → {{D30result}}</span> — {{D30message.description}}
+</div>
+{{/if}}