UX-15: setup-only mode, and the wizard fixes F1, F2, meter, step 1

A new install names no inverter. When that is the startup gate's only
refusal, the add-on now serves the setup wizard in setup-only mode instead
of exiting 78. It builds no controller, MQTT client or meter task, its
HomeAssistant is read-only (every service call refuses before sending),
Controller refuses a read-only HomeAssistant, and /action answers 409.
Any other refusal still exits 78. DECISIONS/UX-15-setup-only-mode.md.

Wizard fixes from the UX-13 P4 test:
- F1: /config/validate converts what it can, so a conversion error blocks
  its own step and the live checks still run; save 422 carries steps.
- F2: saves send the model the page opened (base); only keys this page
  changed are written onto the blob stored now.
- A meter entity missing from Home Assistant is red on the last step.
- Step 1 says the reading went down after a skip that followed a fall.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

goodwe_controller/app/static/app.js

@@ -94,11 +94,13 @@
   function render() {
     renderPill();
     const structured = S.now && S.plan && !S.home_error;
-    banner($("#home-banner"), S.level, S.banner, structured ? S.state.sub : "", S.level === "bad" ? "alert" : null);
+    // UX-15: setup-only mode commands nothing and has no control to offer.
+    const setup = S.setup_only === true;
+    banner($("#home-banner"), S.level, S.banner, structured ? S.state.sub : setup ? t("setup_only.description") : "", S.level === "bad" ? "alert" : null);
     ["#c-now", "#c-plan", "#c-peak", "#c-attn"].forEach((id) => { $(id).hidden = !structured; });
     if (structured) { renderNow(); renderPlan(); renderPeak(); renderAttention(); }
-    renderControl(structured);
-    renderDetails(!structured);
+    renderControl(structured, setup);
+    renderDetails(!structured && !setup);
     renderBatteries();
   }
 
@@ -270,12 +272,15 @@
     badge.textContent = n; badge.hidden = !n;
     badge.classList.toggle("bad", list.some((a) => a.severity === "alarm"));
   }
-  function renderControl(structured) {
+  function renderControl(structured, setup) {
     const running = structured ? S.control.running : null;
     const btn = $("#btn-ctl");
     btn.textContent = running === false ? t("control.start") : t("control.stop");
     btn.className = "btn" + (running === false ? " primary" : "");
-    $("#ctl-text").textContent = structured ? S.control.text : "";
+    btn.hidden = !!setup;
+    $("#btn-setup").hidden = !setup;
+    $("#c-ctl .more").hidden = !!setup;
+    $("#ctl-text").textContent = structured ? S.control.text : setup ? t("setup_only.control") : "";
     $("#hint").textContent = S.hint || "";
     const docs = $("#docs-link");
     if (structured && S.control.docs_url) { docs.href = S.control.docs_url; docs.hidden = false; } else docs.hidden = true;

goodwe_controller/app/static/index.html

@@ -72,6 +72,7 @@
     <div class="small" id="ctl-text"></div>
     <div class="row" style="margin-top:10px">
       <button class="btn" id="btn-ctl" type="button"></button>
+      <a class="btn primary" id="btn-setup" href="#setup" hidden data-t="setup_only.open"></a>
       <a class="small" id="docs-link" hidden target="_top" rel="noopener" data-t="control.docs"></a>
     </div>
     <div class="tiny muted" id="hint" aria-live="polite" style="margin-top:8px"></div>

goodwe_controller/app/static/settings.js

@@ -533,10 +533,12 @@
     if (input) input.focus({ preventScroll: true });
   }
   // The one save path, for the Installer view and the wizard. After a stale
-  // refusal the page holds the new token, so a second press saves.
+  // refusal the page holds the new token, so a second press saves. `base` is
+  // the model the page opened: only what changed since then is written, onto
+  // what is stored now (UX-15 F2).
   async function postSave(extra) {
     const r = await fetch("config/save", { method: "POST", headers: { "Content-Type": "application/json" },
-                                           body: JSON.stringify(Object.assign({ model: V, fingerprint: FP }, extra || {})) });
+                                           body: JSON.stringify(Object.assign({ model: V, base: ORIG, fingerprint: FP }, extra || {})) });
     const b = await r.json().catch(() => ({}));
     if (r.status === 409 && b.kind === "stale") FP = b.fingerprint || FP;
     return { r, b };
@@ -624,8 +626,10 @@
     if (WZ.kettle && WZ.kettle.sig !== sig) WZ.kettle = null;     // another meter: test again
     const k = WZ.kettle || { sig };
     box.append(h("div", { class: "help" }, WS.kettle.description));
-    const tone = { ok: "ok", flip: "info", none: "warn", unread: "bad", skipped: "warn" }[k.say] || "bad";
-    const words = k.say ? WS.kettle[k.say] : k.before != null ? WS.kettle.before : null;
+    // A skip after the reading went down still says it went down (UX-15).
+    const said = k.say === "skipped" && k.wrong ? "skipped_down" : k.say;
+    const tone = { ok: "ok", flip: "info", none: "warn", unread: "bad", skipped: "warn", skipped_down: "warn" }[said] || "bad";
+    const words = said ? WS.kettle[said] : k.before != null ? WS.kettle.before : null;
     if (words) box.append(h("div", { class: "msg " + (k.say ? tone : "info"), role: "status" },
       say(words.description, { w: k.before != null ? watts(k.before, true) : "", d: k.d != null ? watts(k.d) : "" })));
     const busy = (b) => { b.disabled = true; };
@@ -715,7 +719,9 @@
     if (!b) { toast(WS.check.failed.description); return; }
     if (WZ.blocked) { toast(WS.check.blocked.description); return; }
     const shadow = shadowValue() === M.setup.shadow.on;
-    ask(shadow ? WS.dialog : WS.dialog_live, async () => {
+    // In setup-only mode nothing runs yet, so no inverter is set to 0 W first.
+    const dlg = M.setup_only ? (shadow ? WS.dialog_setup : WS.dialog_setup_live) : (shadow ? WS.dialog : WS.dialog_live);
+    ask(dlg, async () => {
       wzBanner();
       let res;
       try { res = await postSave({ setup: "done", model: posted() }); } catch (e) { toast(W.toast.failed); return; }