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/components/docs/markdown-viewer.tsx

@@ -0,0 +1,21 @@
+import ReactMarkdown from "react-markdown";
+import remarkGfm from "remark-gfm";
+import { cn } from "@/lib/utils";
+
+export function MarkdownViewer({ content }: { content: string }) {
+  return (
+    <div
+      className={cn(
+        "prose prose-neutral dark:prose-invert max-w-none",
+        "prose-pre:bg-muted prose-pre:text-foreground",
+        // Typography's default inline `code` style is just bold text wrapped in decorative
+        // backtick characters - swap that for the same muted pill used for inline code
+        // elsewhere in the app (see the "no scripts configured" message on the dashboard).
+        "prose-code:before:content-none prose-code:after:content-none",
+        "prose-code:rounded prose-code:bg-muted prose-code:px-1.5 prose-code:py-0.5 prose-code:font-mono prose-code:font-normal prose-code:text-foreground",
+      )}
+    >
+      <ReactMarkdown remarkPlugins={[remarkGfm]}>{content}</ReactMarkdown>
+    </div>
+  );
+}