fix(street-level): re-check after every await; close the old photo; fresh panel views

Address samehkhamis's review on #1113:

- show_street_level checks the turn, the camera's owner (navigation stamp,
  re-taken where its own flight lands, or a press/wheel on the globe) and
  the hiding modes after the flight, the map switch, the layer switch-on and
  the lookup; a photo that opened after either is closed again. The hidden
  panel is also refused before the flight.
- An open photo closes before a new request arms or looks up, so a place
  with no imagery shows its own error.
- The panel posts every view with `fresh`; the inline app opens a billed
  photo only for a fresh one.
- A passed-through view's street_level point moves with a new camera
  position; revealPanel does nothing above 720px, scrolling included.
- Document that the app's own links do not carry `sl`.

docs/SHARE-LINK-FORMAT.md

@@ -51,6 +51,16 @@ military aircraft or satellite. A selected vessel is not followed (the camera
 stays where the user puts it), so a link made then is a place view; vessel
 thing views open, but the app does not make them yet.
 
+## Street-level photos (`sl`)
+
+Views built by `show_in_gods_eye_view` or `src/view/index.js` can add
+`sl=<source>,<lat>,<lon>` to the long form. Once the link has restored, the
+app opens the nearest photo there, or, for a source that bills every load,
+arms the panel so OPEN loads it (see `docs/TOOLS.md`). The app's own links do
+not carry it: the address bar's long form drops `sl` when the camera next
+moves, and the short form has no field for it. A reload or the app's Copy
+Link keeps the lit source, the layer and the map, but not the photo request.
+
 ## Payload
 
 The code is unpadded base64url (`A–Z a–z 0–9 - _`). The decoded bytes are: