feat(theseus): add a page to favorites by hand

The favorites row's right-click menu could only save the current page.
"Add a page…" opens a two-field form: the address (scheme optional,
must be a real host — Chromium's parser happily percent-encodes junk
like "not a url" into a bogus bookmark, so hosts are checked) and a
title that fills itself from the address, brand-cased like the chips,
until you edit it. Duplicates are refused; the site's /favicon.ico is
used for the chip.

chrome.html

@@ -401,6 +401,9 @@
                      color: var(--ink); font: inherit; font-size: 13px; outline: none; }
   .promptbox input:focus { border-color: rgb(from var(--acid) r g b / .55); }
   .promptbox .pact { display: flex; gap: 6px; justify-content: flex-end; margin-top: 10px; }
+  .promptbox .pfield { display: flex; flex-direction: column; gap: 4px; margin-top: 8px; }
+  .promptbox .pfield label { font-size: 11.5px; color: var(--dim); }
+  .promptbox .perr { color: #f6768a; font-size: 12px; margin-top: 8px; }
   .promptbox .pbtn { padding: 6px 12px; border-radius: 6px; border: 1px solid var(--line);
                      background: var(--surface2, #0f1621); color: var(--ink); cursor: pointer;
                      font: inherit; font-size: 12.5px; }
@@ -1121,10 +1124,68 @@
       setTimeout(() => { input.focus(); input.select(); }, 0);
     });
   }
+  // "Add a page…": a two-field form (address + title). The title fills itself
+  // from the address as you type — brand-cased host, same as the chip label —
+  // until you edit it by hand; then it is yours. Resolves { url, title } or null.
+  function normalizeBookmarkUrl(s) {
+    let v = String(s || "").trim();
+    if (!v) return "";
+    if (!/^[a-z][a-z0-9+.-]*:/i.test(v)) v = "https://" + v.replace(/^\/+/, "");
+    try {
+      const u = new URL(v);
+      if (!/^https?:$|^bns:$|^file:$/.test(u.protocol)) return "";
+      // A real host: letters/digits/dots/dashes (IDNA already applied), no
+      // percent-escapes from spaces, and at least one dot or "localhost".
+      if (u.protocol !== "file:" && !(/^[a-z0-9.-]+$/i.test(u.hostname) && (u.hostname.includes(".") || u.hostname === "localhost"))) return "";
+      return u.href;
+    } catch { return ""; }
+  }
+  function inBookmarkForm(initial = {}) {
+    return new Promise((resolve) => {
+      const mask = document.createElement("div"); mask.className = "promptmask";
+      mask.innerHTML = `<div class="promptbox"><div class="plbl">Add a page to favorites</div>`
+        + `<div class="pfield"><label>Address</label><input type="text" class="purl" spellcheck="false" placeholder="example.com or https://…"></div>`
+        + `<div class="pfield"><label>Title</label><input type="text" class="ptitle" spellcheck="false" placeholder="Filled in from the address — edit as you like"></div>`
+        + `<div class="perr" hidden></div>`
+        + `<div class="pact"><button class="pbtn pcancel" type="button">Cancel</button><button class="pbtn primary pok" type="button">Save</button></div></div>`;
+      document.body.appendChild(mask);
+      const url = mask.querySelector(".purl"), title = mask.querySelector(".ptitle"), err = mask.querySelector(".perr");
+      url.value = String(initial.url ?? ""); title.value = String(initial.title ?? "");
+      let titleTouched = !!title.value;
+      const autoTitle = () => {
+        if (titleTouched) return;
+        const norm = normalizeBookmarkUrl(url.value);
+        let host = ""; try { host = norm ? new URL(norm).hostname.replace(/^www\./, "") : ""; } catch {}
+        title.value = host ? bookmarkShortLabel("", host) : "";
+      };
+      url.addEventListener("input", autoTitle);
+      title.addEventListener("input", () => { titleTouched = title.value.trim().length > 0; if (!titleTouched) autoTitle(); });
+      const done = (val) => { try { mask.remove(); } catch {} document.removeEventListener("keydown", key); resolve(val); };
+      const submit = () => {
+        const norm = normalizeBookmarkUrl(url.value);
+        if (!norm) { err.textContent = "That doesn't look like a web address."; err.hidden = false; url.focus(); return; }
+        if (bookmarks.some((b) => b.url === norm)) { err.textContent = "Already in your favorites."; err.hidden = false; url.focus(); return; }
+        let host = ""; try { host = new URL(norm).hostname.replace(/^www\./, ""); } catch {}
+        done({ url: norm, title: title.value.trim() || (host ? bookmarkShortLabel("", host) : norm) });
+      };
+      const key = (e) => { if (e.key === "Escape") done(null); else if (e.key === "Enter") submit(); };
+      document.addEventListener("keydown", key);
+      mask.addEventListener("mousedown", (e) => { if (e.target === mask) done(null); });
+      mask.querySelector(".pcancel").addEventListener("click", () => done(null));
+      mask.querySelector(".pok").addEventListener("click", submit);
+      setTimeout(() => { url.focus(); url.select(); }, 0);
+    });
+  }
+  async function addBookmarkByHand(initial) {
+    const r = await inBookmarkForm(initial);
+    if (!r) return;
+    let favicon = null; try { const u = new URL(r.url); if (/^https?:$/.test(u.protocol)) favicon = `${u.origin}/favicon.ico`; } catch {}
+    T.addBookmark({ title: r.title, url: r.url, favicon });
+  }
   // Right-click context menu on the bookmarks bar. Two modes:
   //   - On a specific bookmark: Open / Edit title / Remove
   //   - On empty area OR the placeholder text: Add current page (or Remove
-  //     if the page is already bookmarked)
+  //     if the page is already bookmarked), and Add a page… by hand
   function closeBmMenu() { const m = document.getElementById("bmMenu"); if (m) m.remove(); }
   function openBmMenu(x, y, ctx) {
     closeBmMenu();
@@ -1147,6 +1208,7 @@
     } else {
       items.push({ label: "Add current page", disabled: true });
     }
+    items.push({ label: "Add a page…", act: () => addBookmarkByHand() });
     const m = document.createElement("div");
     m.id = "bmMenu"; m.className = "ctxmenu";
     m.innerHTML = items.map((it, i) => it.sep