fix(coding-agent): ship omp:// docs to npm consumers

exports resolve to TypeScript source, where the build-time PI_DOCS_EMBED
placeholder is empty and the dev-tree fallback resolved docs to an
unreachable node_modules/docs, so OmpProtocolHandler.complete()/.resolve()
threw ENOENT for every npm/SDK consumer.

- bundle-dist.ts writes the docs corpus to dist/docs-index.generated.txt
  (shipped via package.json files), reusing the same payload it inlines
  into dist/cli.js.
- docs-index.ts reads the shipped embed when the env embed is empty and
  the on-disk docs/ directory is absent, and degrades to an empty index
  (with a warning) instead of propagating ENOENT.
- Added a generator-to-runtime payload round-trip test.

Fixes #8134

packages/coding-agent/scripts/bundle-dist.ts

@@ -69,6 +69,7 @@ async function cleanBundleOutputs(): Promise<void> {
 			.filter(
 				entry =>
 					entry === "cli.js" ||
+					entry === "docs-index.generated.txt" ||
 					entry.endsWith(".node") ||
 					entry.endsWith(".js.map") ||
 					(entry.startsWith("CHANGELOG-") && entry.endsWith(".md")) ||
@@ -85,6 +86,11 @@ async function main(): Promise<void> {
 	// archive the same way compiled binaries do (scripts/build-binary.ts). Reset
 	// afterwards to keep the checked-in placeholder empty.
 	await runCommand(["bun", "--cwd=../stats", "run", "gen:stats"]);
+	// One payload for both consumers: inlined into dist/cli.js via `--define` for
+	// the bundled CLI entrypoint, and written to dist/docs-index.generated.txt so
+	// SDK consumers importing `@oh-my-pi/pi-coding-agent/*` (TypeScript source, no
+	// build-time embed) can still resolve omp:// docs (see src/internal-urls/docs-index.ts).
+	const docsPayload = await buildDocsIndexPayload();
 	try {
 		// Build in-process: the docs embed payload is far larger than Linux's
 		// 128KiB per-argv-string cap, so it can never be passed as a CLI
@@ -96,7 +102,7 @@ async function main(): Promise<void> {
 			external: [...ALWAYS_EXTERNAL, ...RUNTIME_EXTERNAL],
 			define: {
 				"process.env.PI_BUNDLED": JSON.stringify("true"),
-				"process.env.PI_DOCS_EMBED": JSON.stringify((await buildDocsIndexPayload()).payload),
+				"process.env.PI_DOCS_EMBED": JSON.stringify(docsPayload.payload),
 			},
 			minify: {
 				whitespace: true,
@@ -113,6 +119,7 @@ async function main(): Promise<void> {
 		await runCommand(["bun", "--cwd=../stats", "run", "gen:stats:reset"]);
 	}
 	await ensureShebang();
+	await Bun.write(path.join(outDir, "docs-index.generated.txt"), docsPayload.payload);
 	const stat = await fs.stat(cliPath);
 	const elapsedMs = (Bun.nanoseconds() - start) / 1_000_000;
 	process.stdout.write(