Flatten the repo: move everything out of app/ to the root

Now that the CLI and the Next.js app are one package, nesting it inside
app/ served no purpose - the repo root itself becomes the published
npm package. Merges app/.gitignore and app/README.md into the root
versions, drops the now-duplicate app/LICENSE, and updates path
references (README, docs/ARCHITECTURE.md, docs/CONFIG_REFERENCE.md,
package.json's repository.directory) that assumed the app/ nesting.

Also fixes a real bug this surfaced: the in-app docs viewer resolved
docs/ relative to process.cwd(), which only worked by accident when the
CLI happened to be invoked from app/'s parent directory. A first attempt
at fixing it with import.meta.dirname broke instead, for the same
cross-module-graph reason config-path resolution already documented -
Next compiles Route Handlers through a separate module graph that
doesn't preserve source-relative import.meta paths. Fixed by exposing
the app root via TRIGGERSHELL_APP_ROOT (set once in server.ts, where
import.meta *does* resolve correctly), the same pattern already used
for TRIGGERSHELL_CONFIG_PATH.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/cli/lib/network.ts

@@ -0,0 +1,48 @@
+import { spawn } from "node:child_process";
+import net from "node:net";
+
+export function isPortFree(host: string, port: number): Promise<boolean> {
+  return new Promise((resolve) => {
+    const socket = net.connect({ host, port, timeout: 500 });
+    socket.once("connect", () => {
+      socket.destroy();
+      resolve(false);
+    });
+    socket.once("timeout", () => {
+      socket.destroy();
+      resolve(true);
+    });
+    socket.once("error", () => {
+      resolve(true);
+    });
+  });
+}
+
+export async function waitUntilReady(
+  url: string,
+  timeoutMs: number,
+  intervalMs = 400,
+): Promise<boolean> {
+  const deadline = Date.now() + timeoutMs;
+  while (Date.now() < deadline) {
+    try {
+      const response = await fetch(url, { signal: AbortSignal.timeout(1500) });
+      if (response.status === 200) return true;
+    } catch {
+      // not ready yet
+    }
+    await new Promise((resolve) => setTimeout(resolve, intervalMs));
+  }
+  return false;
+}
+
+export function openBrowser(url: string): void {
+  const command =
+    process.platform === "darwin" ? "open" : process.platform === "win32" ? "start" : "xdg-open";
+  const args = process.platform === "win32" ? ["", url] : [url];
+  try {
+    spawn(command, args, { detached: true, stdio: "ignore", shell: process.platform === "win32" }).unref();
+  } catch {
+    // best-effort - not fatal if no browser opener is available
+  }
+}