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`.

changelog.d/1113-show-street-level.md

@@ -28,5 +28,9 @@
   failing source is reported as an error, not as missing imagery; and
   Mapillary's nearest search gives up after 12 seconds. On a phone the panel
   scrolls into view, and in embed mode EXPAND stays open while cockpit,
-  recording and scene playback hide the photo (Said Turksever, @asturksever,
-  #1113).
+  recording and scene playback hide the photo. The action checks again after
+  every wait: a navigation or a drag of the globe, or a mode that hides the
+  panel, stops it before a photo loads for a place the user left or in a
+  panel nobody sees, and a request that finds nothing closes the previous
+  photo. The panel's later results open a billed photo only when they are
+  fresh too (Said Turksever, @asturksever, #1113).