feat(settings): retire the third-party plugin integrations

Settings → Integrations offered install cards for the Claude Code and
Cursor provider plugins. They are gone: the section, its plugin catalog,
its own i18n module and tests, the settings search entries, the page
keywords, and the two sprite icons only it used. The page now holds the
built-in GitHub and Linear cards, so it is hidden in VS Code where neither
applies; its title and description live in the settings dictionaries.

Docs follow: the Integrations page in every locale now documents GitHub
(pointing at its own page) and Linear in full, the GitHub page names
Settings → Integrations as the place to connect and covers linking an
issue or PR to a message, and the Providers pages no longer promise Claude
or Cursor subscriptions.

Claude-Session: https://claude.ai/code/session_01HB9wdLQoZX2vfyDjwv6Rso

scripts/generate-icon-sprite.mjs

@@ -22,16 +22,6 @@ const customIconData = new Map([
     "openchamber",
     `<polygon points="12 2.5 3.5 7.4 3.5 17.2 12 22.1 20.5 17.2 20.5 7.4" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/><polyline points="3.5 7.4 12 12.3 20.5 7.4" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/><line x1="12" y1="12.3" x2="12" y2="22.1" stroke="currentColor" stroke-width="1.8" stroke-linecap="round"/><path d="m12 5.5 3.7 2.1L12 9.7 8.3 7.6 12 5.5Zm0 1.5-1 .6 1 .6 1-.6-1-.6Z" fill="currentColor" fill-rule="evenodd"/>`,
   ],
-  // Claude spark — official Anthropic mark (Simple Icons path), monochrome.
-  [
-    "claude-code",
-    `<path d="m4.7144 15.9555 4.7174-2.6471.079-.2307-.079-.1275h-.2307l-.7893-.0486-2.6956-.0729-2.3375-.0971-2.2646-.1214-.5707-.1215-.5343-.7042.0546-.3522.4797-.3218.686.0608 1.5179.1032 2.2767.1578 1.6514.0972 2.4468.255h.3886l.0546-.1579-.1336-.0971-.1032-.0972L6.973 9.8356l-2.55-1.6879-1.3356-.9714-.7225-.4918-.3643-.4614-.1578-1.0078.6557-.7225.8803.0607.2246.0607.8925.686 1.9064 1.4754 2.4893 1.8336.3643.3035.1457-.1032.0182-.0728-.164-.2733-1.3539-2.4467-1.445-2.4893-.6435-1.032-.17-.6194c-.0607-.255-.1032-.4674-.1032-.7285L6.287.1335 6.6997 0l.9957.1336.419.3642.6192 1.4147 1.0018 2.2282 1.5543 3.0296.4553.8985.2429.8318.091.255h.1579v-.1457l.1275-1.706.2368-2.0947.2307-2.6957.0789-.7589.3764-.9107.7468-.4918.5828.2793.4797.686-.0668.4433-.2853 1.8517-.5586 2.9021-.3643 1.9429h.2125l.2429-.2429.9835-1.3053 1.6514-2.0643.7286-.8196.85-.9046.5464-.4311h1.0321l.759 1.1293-.34 1.1657-1.0625 1.3478-.8804 1.1414-1.2628 1.7-.7893 1.36.0729.1093.1882-.0183 2.8535-.607 1.5421-.2794 1.8396-.3157.8318.3886.091.3946-.3278.8075-1.967.4857-2.3072.4614-3.4364.8136-.0425.0304.0486.0607 1.5482.1457.6618.0364h1.621l3.0175.2247.7892.522.4736.6376-.079.4857-1.2142.6193-1.6393-.3886-3.825-.9107-1.3113-.3279h-.1822v.1093l1.0929 1.0686 2.0035 1.8092 2.5075 2.3314.1275.5768-.3218.4554-.34-.0486-2.2039-1.6575-.85-.7468-1.9246-1.621h-.1275v.17l.4432.6496 2.3436 3.5214.1214 1.0807-.17.3521-.6071.2125-.6679-.1214-1.3721-1.9246L14.38 17.959l-1.1414-1.9428-.1397.079-.674 7.2552-.3156.3703-.7286.2793-.6071-.4614-.3218-.7468.3218-1.4753.3886-1.9246.3157-1.53.2853-1.9004.17-.6314-.0121-.0425-.1397.0182-1.4328 1.9672-2.1796 2.9446-1.7243 1.8456-.4128.164-.7164-.3704.0667-.6618.4008-.5889 2.386-3.0357 1.4389-1.882.929-1.0868-.0062-.1579h-.0546l-6.3385 4.1164-1.1293.1457-.4857-.4554.0608-.7467.2307-.2429 1.9064-1.3114Z" fill="currentColor"/>`,
-  ],
-  // Cursor two-cursor mark — official (Simple Icons path), monochrome.
-  [
-    "cursor",
-    `<path d="M11.503.131 1.891 5.678a.84.84 0 0 0-.42.726v11.188c0 .3.162.575.42.724l9.609 5.55a1 1 0 0 0 .998 0l9.61-5.55a.84.84 0 0 0 .42-.724V6.404a.84.84 0 0 0-.42-.726L12.497.131a1.01 1.01 0 0 0-.996 0M2.657 6.338h18.55c.263 0 .43.287.297.515L12.23 22.918c-.062.107-.229.064-.229-.06V12.335a.59.59 0 0 0-.295-.51l-9.11-5.257c-.109-.063-.064-.23.061-.23" fill="currentColor"/>`,
-  ],
   // Command Code — corner squares + center square (official logo geometry).
   [
     "command-code",