feat(theseus): hold or right-click Back/Forward for the history list

Holding Back or Forward for 450 ms (or right-clicking it) pops a native
menu of the tab's history entries in that direction — nearest first, up to
15, titled with the page title and host — and picking one jumps straight
to it. A hold swallows the click that would otherwise fire on release, so
a long press never also goes back one page.

chrome.html

@@ -559,6 +559,27 @@
   $("search").addEventListener("keydown", (e) => { if (e.key === "Enter") { const q = $("search").value.trim(); if (q) T.search(q); } });
   $("back").onclick = () => T.back();
   $("fwd").onclick = () => T.forward();
+  // Hold Back/Forward (or right-click) for the history list, like Chrome.
+  // A hold longer than 450 ms opens the native menu and swallows the click
+  // that would otherwise fire on release.
+  for (const [id, dir] of [["back", "back"], ["fwd", "forward"]]) {
+    const btn = $(id);
+    let timer = null, held = false;
+    const open = () => {
+      held = true;
+      const r = btn.getBoundingClientRect();
+      T.navHistoryMenu && T.navHistoryMenu(dir, { x: r.left, y: r.bottom });
+    };
+    btn.addEventListener("mousedown", (e) => {
+      if (e.button !== 0 || btn.disabled) return;
+      held = false; clearTimeout(timer); timer = setTimeout(open, 450);
+    });
+    const cancel = () => { clearTimeout(timer); timer = null; };
+    btn.addEventListener("mouseup", cancel);
+    btn.addEventListener("mouseleave", cancel);
+    btn.addEventListener("click", (e) => { if (held) { held = false; e.stopImmediatePropagation(); e.preventDefault(); } }, true);
+    btn.addEventListener("contextmenu", (e) => { e.preventDefault(); if (!btn.disabled) open(); held = false; });
+  }
   // Shift-click on the reload button = hard reload (bypass cache), same
   // convention as Chrome/Firefox. Keyboard alternative: Ctrl+Shift+R.
   $("reload").onclick = (e) => T.reload(e.shiftKey);

main.js

@@ -4189,6 +4189,32 @@ ipcMain.handle("registry-menu-popup", (e, rect) => {
   const y = Math.max(0, Math.round(chromeBounds.y + (rect?.y || 0)));
   popup.popup({ window: win, x, y });
 });
+// Back/Forward history menu (press-and-hold or right-click on the buttons).
+// Lists up to 15 entries in the requested direction, nearest first, from the
+// active tab's navigation history; picking one jumps straight to it.
+ipcMain.handle("nav-history-menu", (e, dir, rect) => {
+  if (chrome && e.sender !== chrome.webContents) throw new Error("nav-history-menu: untrusted sender");
+  const t = activeTab(); const wc = t?.view?.webContents;
+  if (!wc) return false;
+  const nh = wc.navigationHistory;
+  const entries = nh.getAllEntries();
+  const cur = nh.getActiveIndex();
+  const picks = [];
+  if (dir === "forward") for (let i = cur + 1; i < entries.length && picks.length < 15; i++) picks.push(i);
+  else for (let i = cur - 1; i >= 0 && picks.length < 15; i--) picks.push(i);
+  if (!picks.length) return false;
+  const label = (en) => {
+    const title = String(en.title || "").trim();
+    let host = ""; try { host = new URL(en.url).host; } catch {}
+    const text = title || en.url || "";
+    return (text.length > 60 ? text.slice(0, 57) + "…" : text) + (host && title ? `  —  ${host}` : "");
+  };
+  const template = picks.map((i) => ({ label: label(entries[i]), click: () => { try { nh.goToIndex(i); } catch {} } }));
+  const popup = Menu.buildFromTemplate(template);
+  const chromeBounds = chrome ? chrome.getBounds() : { x: 0, y: 0 };
+  popup.popup({ window: win, x: Math.max(0, Math.round(chromeBounds.x + (rect?.x || 0))), y: Math.max(0, Math.round(chromeBounds.y + (rect?.y || 0))) });
+  return true;
+});
 ipcMain.handle("collision-state", () => ({
   policy: settings.collisionPolicy,
   byName: collisions.byName,

preload.js

@@ -21,6 +21,9 @@ contextBridge.exposeInMainWorld("theseus", {
   goHome: () => ipcRenderer.invoke("go-home"),
   back: () => ipcRenderer.invoke("go-back"),
   forward: () => ipcRenderer.invoke("go-forward"),
+  // Press-and-hold / right-click on Back or Forward: native menu of the
+  // tab's history entries in that direction; picking one jumps to it.
+  navHistoryMenu: (dir, rect) => ipcRenderer.invoke("nav-history-menu", dir, rect),
   reload: (hard) => ipcRenderer.invoke("reload", !!hard),
   stop: () => ipcRenderer.invoke("stop"),
   toggleTor: () => ipcRenderer.invoke("toggle-tor"),