fix(ui): name the missing provider key on a key-gated layer row (#575)

Supersedes #296 by @Matthew-Selvam, ported onto the current component layout with fixes from review.

Verified before merge: format, package boundaries, unit suite, build, and the browser tracking suite; a browser harness for the change where one applies; adversarial review applied.

Co-authored-by: Matthew-Selvam <[email protected]>

docs/CURRENT-STATE.md

@@ -787,7 +787,13 @@ fetching, trailing-24-hour filtering and partial-success caching are unchanged.
 > is present — everyone gets the same tile.
 >
 > Keyless, the honest surface is the **layer row**, which reads
-> `UNAVAILABLE · NASA FIRMS · LIVE · KEY REQUIRED`, and the earthquakes half
+> `UNAVAILABLE · NASA FIRMS · LIVE · KEY REQUIRED`. Its control also names the
+> key: hovering it, and its accessible name, read
+> `Needs FIRMS_MAP_KEY — add it in Provider Settings`. A layer declares which
+> key it needs as a key-registry id and reports `stats.keyRequired` while that
+> key is absent; the panel builds the text from the pair, and produces none for
+> a layer that needs no key, already holds one, or names a key the registry does
+> not recognise. The earthquakes half
 > still delivers in full. The shared loading reducer now treats an explicitly
 > declared missing optional key as a configured terminal state rather than a
 > failed multi-layer mission, so the global chip completes without showing