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/app/api/runs/[runId]/route.ts

@@ -0,0 +1,21 @@
+export const dynamic = "force-dynamic";
+
+import { eq } from "drizzle-orm";
+import { requireAuth, unauthorizedResponse } from "@/lib/auth/guard";
+import { getDb } from "@/lib/db/client";
+import { runs } from "@/lib/db/schema";
+
+export async function GET(
+  request: Request,
+  { params }: { params: Promise<{ runId: string }> },
+) {
+  const auth = await requireAuth(request);
+  if (!auth.authenticated) return unauthorizedResponse();
+
+  const { runId } = await params;
+  const db = getDb();
+  const run = db.select().from(runs).where(eq(runs.id, runId)).get();
+  if (!run) return Response.json({ error: "Run not found" }, { status: 404 });
+
+  return Response.json(run);
+}