refactor(js): app.js 를 브라우저 네이티브 ESM 모듈로 분할

public/js/{util,ui,reactions,modals,comments,feed,main}.js 로 분리하고
dashboard/project 에서 <script type="module" src="/public/js/main.js"> 로 로드.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

public/js/comments.js

@@ -0,0 +1,43 @@
+// 댓글 — 답글 타깃 설정 · Enter 등록 · 삭제 확인. (모달/단독 페이지 공용)
+import { $ } from "./util.js";
+
+export function initComments() {
+  document.addEventListener("click", (e) => {
+    const rb = e.target.closest("[data-reply-to]");
+    if (rb) {
+      e.preventDefault();
+      const scope = rb.closest(".modal") || document;
+      const parentInput = $('input[name="parent_id"]', scope);
+      const banner = $(".reply-banner", scope);
+      const ta = $(".comment-input", scope);
+      if (parentInput) parentInput.value = rb.getAttribute("data-reply-to");
+      if (banner) {
+        banner.hidden = false;
+        const who = $(".reply-banner-name", banner);
+        if (who) who.textContent = rb.getAttribute("data-reply-name") || "";
+      }
+      if (ta) { ta.placeholder = "답글을 입력하세요…"; ta.focus(); }
+      return;
+    }
+    if (e.target.closest("[data-cancel-reply]")) {
+      e.preventDefault();
+      const scope = e.target.closest(".modal") || document;
+      const pi = $('input[name="parent_id"]', scope); if (pi) pi.value = "";
+      const bn = $(".reply-banner", scope); if (bn) bn.hidden = true;
+      const ta = $(".comment-input", scope); if (ta) ta.placeholder = "댓글을 입력하세요…";
+      return;
+    }
+    const del = e.target.closest("[data-confirm]");
+    if (del && !window.confirm(del.getAttribute("data-confirm"))) e.preventDefault();
+  });
+
+  // Enter 등록 / Shift+Enter 줄바꿈
+  document.addEventListener("keydown", (e) => {
+    const ta = e.target;
+    if (ta && ta.classList && ta.classList.contains("comment-input") && e.key === "Enter" && !e.shiftKey) {
+      e.preventDefault();
+      const form = ta.closest("form");
+      if (form && ta.value.trim()) form.submit();
+    }
+  });
+}