feat(runtime): replace tokio+reqwest with asupersync async runtime

- Add HTTP adapter layer (src/http.rs) wrapping asupersync h1 client
- Migrate gitlab client, graphql, and ollama to HTTP adapter
- Swap entrypoint from #[tokio::main] to RuntimeBuilder::new().block_on()
- Rewrite signal handler for asupersync (RuntimeHandle::spawn + ctrl_c())
- Migrate rate limiter sleeps to asupersync::time::sleep(wall_now(), d)
- Add asupersync-native HTTP integration tests
- Convert timeline_seed_tests to RuntimeBuilder pattern

Phases 1-3 of asupersync migration (atomic: code won't compile without all pieces).

src/cli/commands/ingest/run.rs

@@ -271,11 +271,11 @@ async fn run_ingest_inner(
 
     let token = config.gitlab.resolve_token()?;
 
-    let client = GitLabClient::new(
+    let client = Arc::new(GitLabClient::new(
         &config.gitlab.base_url,
         &token,
         Some(config.sync.requests_per_second),
-    );
+    ));
 
     let projects = get_projects_to_sync(&conn, &config.projects, project_filter)?;
 
@@ -352,7 +352,7 @@ async fn run_ingest_inner(
 
     let project_results: Vec<Result<ProjectIngestOutcome>> = stream::iter(projects.iter())
         .map(|(local_project_id, gitlab_project_id, path)| {
-            let client = client.clone();
+            let client = Arc::clone(&client);
             let db_path = db_path.clone();
             let config = config.clone();
             let resource_type = resource_type_owned.clone();