feat(sanity): implement youtube transcript intelligence and nightly dataset sync (#696)

- Add transcript document schema with cues, chapters, stats, and metadata
- Add transcript reference to content partial inherited by posts, podcasts, pages, lessons, and courses
- Implement sync-youtube-transcript Sanity function with YouTube Data API v3 and InnerTube caption fetching
- Restrict transcript sync execution to production dataset and enforce YOUTUBE_API_KEY
- Implement sync-nightly-dataset scheduled function copying production -> dev nightly at 04:00 UTC
- Update sanity.blueprint.ts registering both functions
- Update search and shared queries to index and project transcripts

Author: codercatdev

apps/sanity/extract.json

@@ -0,0 +1,86 @@
+import { scheduledEventHandler } from "@sanity/functions";
+
+export const handler = scheduledEventHandler(async ({ context }) => {
+	console.log("[Sync Nightly Dataset] Starting scheduled dataset sync...");
+
+	const projectId =
+		context.clientOptions?.projectId ||
+		process.env.SANITY_STUDIO_PROJECT_ID ||
+		"hfh83o0w";
+	const token =
+		context.clientOptions?.token || process.env.SANITY_AUTH_TOKEN;
+
+	if (!token) {
+		throw new Error(
+			"[Sync Nightly Dataset] Missing Sanity API token (neither context.clientOptions.token nor SANITY_AUTH_TOKEN is present).",
+		);
+	}
+
+	const apiHost =
+		context.clientOptions?.apiHost || "https://api.sanity.io";
+	const apiVersion = "v2025-09-30";
+
+	const targetDataset = "dev";
+	const sourceDataset = "production";
+
+	console.log(
+		`[Sync Nightly Dataset] Resetting dataset "${targetDataset}" from source "${sourceDataset}" for project ${projectId}...`,
+	);
+
+	// 1. Delete existing target dataset (dev) if it exists
+	const deleteUrl = `${apiHost}/${apiVersion}/projects/${projectId}/datasets/${targetDataset}`;
+	console.log(`[Sync Nightly Dataset] Deleting existing dataset "${targetDataset}": ${deleteUrl}`);
+
+	const deleteResp = await fetch(deleteUrl, {
+		method: "DELETE",
+		headers: {
+			Authorization: `Bearer ${token}`,
+		},
+	});
+
+	if (deleteResp.ok) {
+		console.log(
+			`[Sync Nightly Dataset] Target dataset "${targetDataset}" deleted successfully (HTTP ${deleteResp.status}).`,
+		);
+	} else if (deleteResp.status === 404) {
+		console.log(
+			`[Sync Nightly Dataset] Target dataset "${targetDataset}" does not exist yet (HTTP 404). Proceeding to clone.`,
+		);
+	} else {
+		const deleteError = await deleteResp.text();
+		console.warn(
+			`[Sync Nightly Dataset] Notice when deleting dataset "${targetDataset}": HTTP ${deleteResp.status} — ${deleteError}`,
+		);
+	}
+
+	// 2. Clone source dataset (production) to target (dev) via Sanity Enterprise Copy API
+	const copyUrl = `${apiHost}/${apiVersion}/projects/${projectId}/datasets/${sourceDataset}/copy`;
+	console.log(
+		`[Sync Nightly Dataset] Copying "${sourceDataset}" -> "${targetDataset}": ${copyUrl}`,
+	);
+
+	const copyResp = await fetch(copyUrl, {
+		method: "PUT",
+		headers: {
+			Authorization: `Bearer ${token}`,
+			"Content-Type": "application/json",
+		},
+		body: JSON.stringify({
+			targetDataset,
+			skipHistory: true,
+		}),
+	});
+
+	if (!copyResp.ok) {
+		const errorText = await copyResp.text();
+		throw new Error(
+			`[Sync Nightly Dataset] Failed to initiate dataset copy from "${sourceDataset}" to "${targetDataset}": HTTP ${copyResp.status} — ${errorText}`,
+		);
+	}
+
+	const copyResult = await copyResp.json().catch(() => ({}));
+	console.log(
+		`[Sync Nightly Dataset] Successfully initiated dataset copy from "${sourceDataset}" to "${targetDataset}":`,
+		copyResult,
+	);
+});