Merge origin/i18n-spanish: whole-interface translation meets KartaView

This branch moved twice at once: upstream merged KartaView (#1121, a
third keyless street-level provider sharing a new lineCoverage.js), and
the remote i18n-spanish gained the whole-interface translation work
(1993 catalog entries, translateKnown, data-i18n-runtime, the unmarked-
string detector in npm run i18n) built on the Street View merge.

Integration keeps the remote's mechanisms and re-adds KartaView on top:

- presentMeta: remote's translateHint for coverage hints, plus the
  KartaView count line as its own literal tn pair (Russian plurals need
  the noun inside the template; keyed off coverageLabel.noun with the
  sequences pair as the default).
- uiState: upstream's highlightsSequence legend gate (KartaView's lines
  do not highlight) with t('Selected').
- layer-panels.html: remote's data-i18n/data-i18n-runtime hooks plus the
  sl-since-note wiring KartaView's upload-date SINCE note needs.
- kartaview viewer: the photo-navigation aria-label and img alt go
  through t(), as the remote's unmarked-string detector requires.
- catalogs: remote's 1987-entry base (its refined keys supersede this
  branch's earlier Street View wording) plus the KartaView entries:
  coverage hints, the upload-date note, the streets count line (with
  Russian one/few/many/other forms) and the viewer strings.

npm run i18n: complete, no unmarked strings. npm test: 6520/6522 (the
one failure is the pre-existing environmental OPENAI_API_KEY leak in
devFreshDotenv). Build passes.

src/ui/styles/street-level.css

@@ -213,6 +213,20 @@ button.sl-status:focus-visible {
   display: none;
 }
 
+/* Longer translations: rather than squeeze the hint into a narrow column
+   beside the button, put the button on its own line when both do not fit. */
+html:not([lang='en']) .sl-meta-row {
+  flex-wrap: wrap;
+}
+
+html:not([lang='en']) .sl-meta-row .sl-meta {
+  flex: 1 1 14em;
+}
+
+html:not([lang='en']) .sl-meta-row .sl-nearest-btn {
+  flex: 1 0 auto;
+}
+
 /* ── Errors ──────────────────────────────────────────────────────────────── */
 .sl-error {
   font-family: var(--font-sans);