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/lib/runner/events.ts

@@ -0,0 +1,18 @@
+import { EventEmitter } from "node:events";
+import type { ServerMessage } from "../ws/protocol";
+
+declare global {
+  var __triggershellRunEvents: EventEmitter | undefined;
+}
+
+/** Decouples the run engine from the WS transport: the engine emits, ws/server.ts broadcasts.
+ * Anchored on `globalThis` because Next compiles Route Handlers through its own module graph,
+ * separate from the modules `server.ts` requires directly via tsx - a plain module-level
+ * singleton would silently end up duplicated (one copy per graph) instead of shared. */
+export const runEvents: EventEmitter = globalThis.__triggershellRunEvents ?? new EventEmitter();
+globalThis.__triggershellRunEvents = runEvents;
+runEvents.setMaxListeners(0);
+
+export function emitRunMessage(message: ServerMessage) {
+  runEvents.emit("message", message);
+}