perf: Concurrent resource event fetching, remove unnecessary async

client.rs:
- fetch_all_resource_events() now uses tokio::try_join!() to fire all
  three API requests (state, label, milestone events) concurrently
  instead of awaiting each sequentially. For entities with many events,
  this reduces wall-clock time by up to ~3x since the three independent
  HTTP round-trips overlap.

main.rs:
- Removed async from handle_issues() and handle_mrs(). These functions
  perform only synchronous database queries and formatting; they never
  await anything. Removing the async annotation avoids the overhead of
  an unnecessary Future state machine and makes the sync nature of
  these code paths explicit.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/main.rs

@@ -72,8 +72,8 @@ async fn main() {
     let quiet = cli.quiet;
 
     let result = match cli.command {
-        Commands::Issues(args) => handle_issues(cli.config.as_deref(), args, robot_mode).await,
-        Commands::Mrs(args) => handle_mrs(cli.config.as_deref(), args, robot_mode).await,
+        Commands::Issues(args) => handle_issues(cli.config.as_deref(), args, robot_mode),
+        Commands::Mrs(args) => handle_mrs(cli.config.as_deref(), args, robot_mode),
         Commands::Search(args) => handle_search(cli.config.as_deref(), args, robot_mode).await,
         Commands::Stats(args) => handle_stats(cli.config.as_deref(), args, robot_mode).await,
         Commands::Embed(args) => handle_embed(cli.config.as_deref(), args, robot_mode).await,
@@ -284,7 +284,7 @@ fn handle_error(e: Box<dyn std::error::Error>, robot_mode: bool) -> ! {
 // Primary command handlers
 // ============================================================================
 
-async fn handle_issues(
+fn handle_issues(
     config_override: Option<&str>,
     args: IssuesArgs,
     robot_mode: bool,
@@ -334,7 +334,7 @@ async fn handle_issues(
     Ok(())
 }
 
-async fn handle_mrs(
+fn handle_mrs(
     config_override: Option<&str>,
     args: MrsArgs,
     robot_mode: bool,