apps-config: drop the foreign chains' logos, links and identity icons

- 87 chain and all 185 node logos were referenced by nothing once the
  foreign endpoints went; the images are removed and imgConvert no longer
  generates a nodes set. Pezkuwi and Zagros logos remain.
- External links: none of the 14 services serves a Pezkuwi chain. Most
  are third-party sites whose chain keys had been renamed by the rebrand
  (on Zagros they linked to commonwealth, subsquare and others for
  another chain's data); stats., statescan. and scan.pezkuwichain.io do
  not resolve, explorer.pezkuwichain.io is a placeholder and treasury./
  governance. redirect back to this app. externalLinks is empty until a
  service indexes a Pezkuwi chain; their logos are removed too.
- Identity icons: the centrifuge, joystream, litentry, dicle and paseo
  entries are removed.

scripts/imgConvert.mjs

@@ -33,7 +33,7 @@ const all = {};
 /** @type {Record<string, number>} */
 const oversized = {};
 
-for (const dir of ['extensions', 'external', 'chains', 'nodes']) {
+for (const dir of ['extensions', 'external', 'chains']) {
   const sub = path.join('packages/apps-config/src/ui/logos', dir);
   const generated = path.join(sub, 'generated');
   /** @type {Record<string, string>} */