Set sourceType to skills_sh for skills imported from skills.sh URLs

When skills are imported via skills.sh URLs or key-style imports
(org/repo/skill), the stored sourceType is now "skills_sh" with the
original skills.sh URL as sourceLocator, instead of "github" with the
resolved GitHub URL.

- Add "skills_sh" to CompanySkillSourceType and CompanySkillSourceBadge
- Track originalSkillsShUrl in parseSkillImportSourceInput
- Override sourceType/sourceLocator in importFromSource for skills.sh
- Handle skills_sh in key derivation, source info, update checks,
  file reads, portability export, and UI badge rendering

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/services/company-export-readme.ts

@@ -59,7 +59,7 @@ function mermaidEscape(s: string): string {
 function skillSourceLabel(skill: CompanyPortabilityManifest["skills"][number]): string {
   if (skill.sourceLocator) {
     // For GitHub or URL sources, render as a markdown link
-    if (skill.sourceType === "github" || skill.sourceType === "url") {
+    if (skill.sourceType === "github" || skill.sourceType === "skills_sh" || skill.sourceType === "url") {
       return `[${skill.sourceType}](${skill.sourceLocator})`;
     }
     return skill.sourceLocator;