Allow CEO agents to update company branding (name, description, logo, color)

- Add updateCompanyBrandingSchema restricting agent-updatable fields to name,
  description, brandColor, and logoAssetId
- Update PATCH /api/companies/:companyId to allow CEO agents with branding-only
  fields while keeping admin fields (status, budget, etc.) board-only
- Allow agents to GET /api/companies/:companyId for reading company info
- issuePrefix (company slug) remains protected — not in any update schema
- Document branding APIs in SKILL.md quick reference and api-reference.md

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

packages/shared/src/validators/company.ts

@@ -22,3 +22,13 @@ export const updateCompanySchema = createCompanySchema
   });
 
 export type UpdateCompany = z.infer<typeof updateCompanySchema>;
+
+/** Branding-only subset that CEO agents may update. */
+export const updateCompanyBrandingSchema = z.object({
+  name: z.string().min(1).optional(),
+  description: z.string().nullable().optional(),
+  brandColor: z.string().regex(/^#[0-9a-fA-F]{6}$/).nullable().optional(),
+  logoAssetId: logoAssetIdSchema,
+});
+
+export type UpdateCompanyBranding = z.infer<typeof updateCompanyBrandingSchema>;

packages/shared/src/validators/index.ts

@@ -15,8 +15,10 @@ export {
 export {
   createCompanySchema,
   updateCompanySchema,
+  updateCompanyBrandingSchema,
   type CreateCompany,
   type UpdateCompany,
+  type UpdateCompanyBranding,
 } from "./company.js";
 export {
   portabilityIncludeSchema,