Add adapter environment testing infrastructure

Introduce testEnvironment() on ServerAdapterModule with structured
pass/warn/fail diagnostics for all four adapter types (claude_local,
codex_local, process, http). Adds POST test-environment endpoint,
shared types/validators, adapter test implementations, and UI API
client. Includes asset type foundations used by related features.

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

server/src/__tests__/claude-local-adapter-environment.test.ts

@@ -0,0 +1,63 @@
+import { afterEach, describe, expect, it } from "vitest";
+import { testEnvironment } from "@paperclip/adapter-claude-local/server";
+
+const ORIGINAL_ANTHROPIC = process.env.ANTHROPIC_API_KEY;
+
+afterEach(() => {
+  if (ORIGINAL_ANTHROPIC === undefined) {
+    delete process.env.ANTHROPIC_API_KEY;
+  } else {
+    process.env.ANTHROPIC_API_KEY = ORIGINAL_ANTHROPIC;
+  }
+});
+
+describe("claude_local environment diagnostics", () => {
+  it("returns a warning (not an error) when ANTHROPIC_API_KEY is set in host environment", async () => {
+    process.env.ANTHROPIC_API_KEY = "sk-test-host";
+
+    const result = await testEnvironment({
+      companyId: "company-1",
+      adapterType: "claude_local",
+      config: {
+        command: process.execPath,
+        cwd: process.cwd(),
+      },
+    });
+
+    expect(result.status).toBe("warn");
+    expect(
+      result.checks.some(
+        (check) =>
+          check.code === "claude_anthropic_api_key_overrides_subscription" &&
+          check.level === "warn",
+      ),
+    ).toBe(true);
+    expect(result.checks.some((check) => check.level === "error")).toBe(false);
+  });
+
+  it("returns a warning (not an error) when ANTHROPIC_API_KEY is set in adapter env", async () => {
+    delete process.env.ANTHROPIC_API_KEY;
+
+    const result = await testEnvironment({
+      companyId: "company-1",
+      adapterType: "claude_local",
+      config: {
+        command: process.execPath,
+        cwd: process.cwd(),
+        env: {
+          ANTHROPIC_API_KEY: "sk-test-config",
+        },
+      },
+    });
+
+    expect(result.status).toBe("warn");
+    expect(
+      result.checks.some(
+        (check) =>
+          check.code === "claude_anthropic_api_key_overrides_subscription" &&
+          check.level === "warn",
+      ),
+    ).toBe(true);
+    expect(result.checks.some((check) => check.level === "error")).toBe(false);
+  });
+});