feat: add web admin panel for node management

Add Flask panel with login, add/delete nodes, and share link copy.
Generate sing-box config from SQLite; add uninstall script and clean install flow.
Panel served at https://DOMAIN:8444 via nginx.

Co-authored-by: Cursor <cursoragent@cursor.com>

panel/static/app.js

@@ -0,0 +1,74 @@
+function toast(msg) {
+  const el = document.getElementById("toast");
+  el.textContent = msg;
+  el.classList.remove("hidden");
+  setTimeout(() => el.classList.add("hidden"), 2200);
+}
+
+document.querySelectorAll("[data-copy]").forEach((btn) => {
+  btn.addEventListener("click", async () => {
+    const text = btn.dataset.copy;
+    try {
+      await navigator.clipboard.writeText(text);
+      toast("已复制到剪贴板");
+    } catch {
+      toast("复制失败，请手动选择文本");
+    }
+  });
+});
+
+const modal = document.getElementById("modal");
+const addBtn = document.getElementById("addBtn");
+const cancelBtn = document.getElementById("cancelBtn");
+const confirmAddBtn = document.getElementById("confirmAddBtn");
+const nodeName = document.getElementById("nodeName");
+
+if (addBtn) {
+  addBtn.addEventListener("click", () => {
+    nodeName.value = "";
+    modal.classList.remove("hidden");
+    nodeName.focus();
+  });
+}
+
+if (cancelBtn) {
+  cancelBtn.addEventListener("click", () => modal.classList.add("hidden"));
+}
+
+if (confirmAddBtn) {
+  confirmAddBtn.addEventListener("click", async () => {
+    const name = nodeName.value.trim() || "新节点";
+    confirmAddBtn.disabled = true;
+    try {
+      const res = await fetch("/api/nodes", {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ name }),
+      });
+      const data = await res.json();
+      if (!res.ok) throw new Error(data.error || "创建失败");
+      location.reload();
+    } catch (err) {
+      toast(err.message);
+    } finally {
+      confirmAddBtn.disabled = false;
+    }
+  });
+}
+
+document.querySelectorAll(".delete-btn").forEach((btn) => {
+  btn.addEventListener("click", async () => {
+    const id = btn.dataset.id;
+    if (!confirm("确定删除该节点？删除后对应链接将失效。")) return;
+    btn.disabled = true;
+    try {
+      const res = await fetch(`/api/nodes/${id}`, { method: "DELETE" });
+      const data = await res.json();
+      if (!res.ok) throw new Error(data.error || "删除失败");
+      location.reload();
+    } catch (err) {
+      toast(err.message);
+      btn.disabled = false;
+    }
+  });
+});