fix: add IsOrganizationMember check for pin to org dropdown

The pin dropdown now correctly shows the Pin to Organization option
when viewing a repo owned by an org where the user is a member.

🤖 Generated with Claude Code

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

services/context/repo.go

@@ -425,6 +425,11 @@ func repoAssignment(ctx *Context, repo *repo_model.Repository) {
 	if ctx.Repo.Repository.Owner.IsOrganization() {
 		isPinnedToOrg, _ := organization.IsRepoPinned(ctx, ctx.Repo.Repository.OwnerID, ctx.Repo.Repository.ID)
 		ctx.Data["IsRepoPinnedToOrg"] = isPinnedToOrg
+		// Check if user is a member of the org for pin dropdown
+		if ctx.Doer != nil {
+			isMember, _ := organization.IsOrganizationMember(ctx, ctx.Repo.Repository.OwnerID, ctx.Doer.ID)
+			ctx.Data["IsOrganizationMember"] = isMember
+		}
 	}
 	ctx.Data["IsEmptyRepo"] = ctx.Repo.Repository.IsEmpty
 }