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/TOOLS.md

@@ -120,8 +120,11 @@ photo at once; none of them bills per image. A link that follows an entity ignor
 Tools take a view as `VIEW_ARGUMENTS`: an `area` to frame from above, or a
 `camera`, plus `layers`, `style`, `map`, `follow`, `annotations` and
 `street_level`. A tilted camera over an area looks at its center from behind;
-camera fields given with an area override its framing. `resolveViewArguments`
-turns them into a view.
+camera fields given with an area override its framing. A passed-through
+view's `street_level` point moves with a new `area` or camera position (a
+turned camera keeps it). `resolveViewArguments` turns them into a view. The
+app's own links (the address bar, Copy Link, `/share/<code>`) do not carry
+`sl`; see `docs/SHARE-LINK-FORMAT.md`.
 
 ### The God's Eye View panel