Add --skills flag to company export CLI and fix unsupported URL import path

- Add first-class --skills <list> option to `paperclipai company export`,
  passing through to the existing service support for skill selection
- Remove broken `type: "url"` source branch from import command — the shared
  schema and server only accept `inline | github`, so non-GitHub HTTP URLs
  now error clearly instead of failing at validation
- Export isHttpUrl/isGithubUrl helpers for testability
- Add server tests for skills-filtered export (selected + fallback)
- Add CLI tests for URL detection helpers

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

cli/src/__tests__/company-import-url.test.ts

@@ -0,0 +1,31 @@
+import { describe, expect, it } from "vitest";
+import { isHttpUrl, isGithubUrl } from "../commands/client/company.js";
+
+describe("isHttpUrl", () => {
+  it("matches http URLs", () => {
+    expect(isHttpUrl("http://example.com/foo")).toBe(true);
+  });
+
+  it("matches https URLs", () => {
+    expect(isHttpUrl("https://example.com/foo")).toBe(true);
+  });
+
+  it("rejects local paths", () => {
+    expect(isHttpUrl("/tmp/my-company")).toBe(false);
+    expect(isHttpUrl("./relative")).toBe(false);
+  });
+});
+
+describe("isGithubUrl", () => {
+  it("matches GitHub URLs", () => {
+    expect(isGithubUrl("https://github.com/org/repo")).toBe(true);
+  });
+
+  it("rejects non-GitHub HTTP URLs", () => {
+    expect(isGithubUrl("https://example.com/foo")).toBe(false);
+  });
+
+  it("rejects local paths", () => {
+    expect(isGithubUrl("/tmp/my-company")).toBe(false);
+  });
+});