fix: add companyId filter to metadata update + export CompanySkillUpdateAuth type

- Scope metadata update WHERE clause to companyId for defence-in-depth
- Add CompanySkillUpdateAuth inferred type export to match other schemas

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/services/company-skills.ts

@@ -2354,7 +2354,7 @@ export function companySkillService(db: Db) {
         await db
           .update(companySkills)
           .set({ metadata: meta, updatedAt: new Date() })
-          .where(eq(companySkills.id, skill.id));
+          .where(and(eq(companySkills.id, skill.id), eq(companySkills.companyId, companyId)));
       }
     }