feat(stalk): add github + youtube profile stalk endpoints

Ported from Shirokami-API scraper/stalk/{github,youtube}.js:
- /stalk/github (GitHub public API profile)
- /stalk/youtube (ytInitialData parse from /videos subpage:
  handles lockupViewModel (new), videoRenderer, gridVideoRenderer,
  shortsLockupViewModel; channel metadata + top-5 videos)

Also fix misc harga-emas main price to smallest-gram (1gr).

src/application/mod.rs

@@ -4,3 +4,4 @@ pub mod downloader;
 pub mod komik;
 pub mod misc;
 pub mod proxy;
+pub mod stalk;

src/application/stalk.rs

@@ -0,0 +1,19 @@
+//! Application use-cases for stalk (profile/user lookups).
+
+use crate::domain::error::ScrapingError;
+use crate::infrastructure::repository::stalk as Repo;
+use serde_json::Value;
+
+/// GitHub user profile stalk.
+pub async fn github(username: &str) -> Result<Value, ScrapingError> {
+    Repo::fetch_github_stalk(username)
+        .await
+        .map_err(ScrapingError::Http)
+}
+
+/// YouTube channel/profile stalk.
+pub async fn youtube(username: &str) -> Result<Value, ScrapingError> {
+    Repo::fetch_youtube_stalk(username)
+        .await
+        .map_err(ScrapingError::Http)
+}