docs: credit and document the Spanish city bike systems

- dataCredits `gbfs`: names the seven PBSC operators, with BiciMAD's
  required "Powered by EMT de Madrid" linking to emtmadrid.es.
- dataCredits `jcdecaux-gbfs`: adds Valenbisi and Sevici.
- DATA_SOURCES.md: a BiciMAD row (Madrid's open-data catalogue publishes
  the feed under EMT's terms, attribution required), one row for the other
  six PBSC feeds (no licence published; attribution to the operator), and
  the JCDecaux row widened to Valencia and Seville.
- CURRENT-STATE.md: the Bikeshare row, and the underscore and
  geofenced-capacity rules in "GBFS upstream bounds".

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/data/dataCredits.js

@@ -305,7 +305,10 @@ export const DATA_CREDITS = [
     html:
       'Bikeshare availability: GBFS operator feeds ' +
       '(e.g. Austin BCycle; Bike Share Toronto, operated by the Toronto Parking Authority; Bike Itaú and Tembici Bogotá, operated by Tembici; ' +
-      'Bicing, Barcelona City Council (B:SM); AMBici, Àrea Metropolitana de Barcelona, operated by nextbike)',
+      'Bicing, Barcelona City Council (B:SM); AMBici, Àrea Metropolitana de Barcelona, operated by nextbike; ' +
+      'BiciMAD, <a href="https://www.emtmadrid.es" target="_blank" rel="noopener">Powered by EMT de Madrid</a>; ' +
+      'Bizi Zaragoza; BIKI, AUVASA (Valladolid); BiciCoruña; Dbizi (Donostia-San Sebastián); ' +
+      'Bilbao Bizi, Bilbao City Council; BicinRivas, Rivas-Vaciamadrid City Council)',
   },
   {
     key: 'urbansharing-gbfs',
@@ -324,7 +327,7 @@ export const DATA_CREDITS = [
   {
     key: 'jcdecaux-gbfs',
     html:
-      'City bikes (Lillestrøm): Bysykkel Lillestrøm, JCDecaux — ' +
+      'City bikes (Lillestrøm, Valencia, Seville): Bysykkel Lillestrøm, Valenbisi, Sevici, JCDecaux — ' +
       '<a href="https://developer.jcdecaux.com/files/Open-Licence-fr.pdf" target="_blank" rel="noopener">Licence Ouverte</a>',
   },
   {