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/ui_text/en.json

@@ -79,6 +79,7 @@
     },
     "toast": {"started": "Control started.", "stopped": "Control stopped.", "done": "Done.", "failed": "That did not work. Try again."},
     "offline": {"name": "Cannot reach the add-on", "description": "The page tries again every 3 seconds."},
+    "setup_only": {"description": "Nothing is sent to any inverter until setup is saved and the add-on restarts.", "control": "Control starts after setup.", "open": "Open Setup"},
     "batteries": {"name": "Batteries", "description": "Battery modes and on and off switches arrive in a later update.", "level": "Level", "now": "Now", "stored": "Stored", "mode": "Mode", "settings": "Change inverter settings"},
     "settings": {"name": "Settings", "description": "The settings are grouped by task below.", "open": "Open the settings page"}
   },
@@ -192,6 +193,7 @@
         "self": {"description": "The add-on reads this meter itself, so Home shows its direction after the restart."},
         "skipped": {"description": "The meter direction is not tested, so check it on Home after the restart."},
         "skipped_wrong": {"description": "The kettle test saw the meter reading go down, so check its direction in step 1 before you start control."},
+        "skipped_down": {"description": "The reading went down when the kettle came on, so check the meter's direction before you start control."},
         "tested": {"description": "The meter direction was tested with a kettle."},
         "needed": {"description": "Do the kettle test first, or skip it."}
       },
@@ -206,6 +208,8 @@
       "shadow": {"name": "Start in shadow mode", "description": "Recommended, because every inverter then stays at 0 W until you turn shadow mode off under Settings."},
       "dialog": {"name": "Save and restart?", "description": "Every inverter is set to 0 W while the add-on restarts, and shadow mode keeps them at 0 W after that.", "yes": "Save and restart"},
       "dialog_live": {"name": "Save and restart?", "description": "Every inverter is set to 0 W while the add-on restarts, and then the new settings apply.", "yes": "Save and restart"},
+      "dialog_setup": {"name": "Save and restart?", "description": "The add-on restarts with these settings, and shadow mode keeps every inverter at 0 W.", "yes": "Save and restart"},
+      "dialog_setup_live": {"name": "Save and restart?", "description": "The add-on restarts with these settings, and then they apply.", "yes": "Save and restart"},
       "done": {"name": "Setup is done", "description": "The add-on restarts in shadow mode now, so open Home in a minute to see what it would do."},
       "done_live": {"name": "Setup is done", "description": "The add-on restarts now, so open Home in a minute to start control."},
       "restart_failed": {"name": "Saved, not running yet", "description": "The restart did not go through, so press Restart now to apply the settings."},