refactor: 模块化前端代码 - 将 main.js 和 main.css 拆分为专用模块

- 移除 main.js 并替换为8个 JS 模块
- 移除 main.css 并替换为7个 CSS 模块
- 更新 base.html 以加载模块化文件
- 通过 index.css 保持完全向后兼容
- 改进代码组织、可维护性和可复用性

static/js/selection.js

@@ -0,0 +1,178 @@
+/**
+ * 文件选择和批量操作相关功能
+ */
+
+/**
+ * 获取所有条目复选框
+ * @returns {NodeListOf<Element>}
+ */
+function getEntryCheckboxes() {
+    return document.querySelectorAll(".entry-checkbox");
+}
+
+/**
+ * 更新全选状态
+ */
+function updateSelectAllState() {
+    const master = document.getElementById("selectAll");
+    if (!master) {
+        return;
+    }
+
+    const checkboxes = Array.from(getEntryCheckboxes());
+    if (checkboxes.length === 0) {
+        master.checked = false;
+        master.indeterminate = false;
+        return;
+    }
+
+    const checkedCount = checkboxes.filter((checkbox) => checkbox.checked).length;
+
+    if (checkedCount === 0) {
+        master.checked = false;
+        master.indeterminate = false;
+    } else if (checkedCount === checkboxes.length) {
+        master.checked = true;
+        master.indeterminate = false;
+    } else {
+        master.checked = false;
+        master.indeterminate = true;
+    }
+}
+
+/**
+ * 切换全选
+ * @param {HTMLInputElement} master - 主复选框
+ */
+function toggleSelectAll(master) {
+    const checkboxes = getEntryCheckboxes();
+    const desiredState = Boolean(master.checked);
+
+    checkboxes.forEach((checkbox) => {
+        checkbox.checked = desiredState;
+    });
+
+    master.indeterminate = false;
+    updateSelectAllState();
+}
+
+/**
+ * 绑定复选框监听器
+ */
+function attachEntryCheckboxListeners() {
+    const master = document.getElementById("selectAll");
+    if (master && !master.dataset.listenerAttached) {
+        master.addEventListener("change", () => toggleSelectAll(master));
+        master.dataset.listenerAttached = "true";
+    }
+
+    getEntryCheckboxes().forEach((checkbox) => {
+        if (!checkbox.dataset.listenerAttached) {
+            checkbox.addEventListener("change", updateSelectAllState);
+            checkbox.dataset.listenerAttached = "true";
+        }
+    });
+
+    updateSelectAllState();
+}
+
+/**
+ * 删除选定的条目
+ */
+async function deleteSelectedEntries() {
+    const selected = Array.from(getEntryCheckboxes()).filter((checkbox) => checkbox.checked);
+
+    if (selected.length === 0) {
+        const statusDiv = updateStatus("✗ 请先选择要删除的项目", "error");
+        hideStatusLater(statusDiv);
+        return;
+    }
+
+    const directories = selected.filter((checkbox) => checkbox.dataset.type === "dir");
+    if (directories.length > 0) {
+        const statusDiv = updateStatus("✗ 暂不支持批量删除文件夹，请仅选择文件", "error");
+        hideStatusLater(statusDiv);
+        return;
+    }
+
+    const files = selected.map((checkbox) => checkbox.value);
+    const confirmMessage =
+        files.length === 1 ? `确定要删除 "${files[0]}" 吗？` : `确定要删除选中的 ${files.length} 个文件吗？`;
+
+    const confirmed = await showConfirm(confirmMessage, {
+        title: "批量删除",
+        confirmLabel: "删除",
+    });
+
+    if (!confirmed) {
+        return;
+    }
+
+    const deleteButton = document.getElementById("deleteTrigger");
+    if (deleteButton) {
+        deleteButton.disabled = true;
+        deleteButton.classList.add("is-disabled");
+    }
+
+    const inProgressStatus = updateStatus(`正在删除 ${files.length} 个文件...`, null);
+
+    const failures = [];
+    let successCount = 0;
+
+    for (const filePath of files) {
+        const result = await deleteFile(filePath, {
+            skipConfirm: true,
+            suppressReload: true,
+            suppressStatus: true,
+        });
+
+        if (result) {
+            successCount += 1;
+        } else {
+            failures.push(filePath);
+        }
+    }
+
+    if (deleteButton) {
+        deleteButton.disabled = false;
+        deleteButton.classList.remove("is-disabled");
+    }
+
+    if (inProgressStatus) {
+        inProgressStatus.style.display = "none";
+    }
+
+    if (failures.length === 0 && successCount > 0) {
+        const statusDiv = updateStatus(`✓ 已删除 ${successCount} 个文件`, "success");
+        hideStatusLater(statusDiv, 3000);
+
+        setTimeout(() => {
+            window.location.reload();
+        }, 1500);
+        return;
+    }
+
+    if (failures.length > 0) {
+        const message =
+            failures.length === files.length ? "✗ 删除失败，请稍后重试" : `删除部分文件失败：${failures.join(", ")}`;
+        const statusDiv = updateStatus(message, "error");
+        hideStatusLater(statusDiv, 4000);
+
+        if (successCount > 0) {
+            setTimeout(() => {
+                window.location.reload();
+            }, 1500);
+        }
+    }
+}
+
+/**
+ * 导出到全局作用域
+ */
+window.SelectionUtils = {
+    getEntryCheckboxes,
+    updateSelectAllState,
+    toggleSelectAll,
+    attachEntryCheckboxListeners,
+    deleteSelectedEntries,
+};