feat(init): add connection status, flush controls, and fix config bundling (#82)

- Rename SegmentConfig.xcconfig to SegmentConfig.conf so Xcode bundles
  it as a resource (xcconfig files are treated as build configs, not
  resources, so the file was never included in the app bundle)
- Add connection status indicator that validates the write key against
  Segment's API on launch (connected/invalid key/demo mode/error)
- Add flush mode selector (auto/manual) with manual flush button
- Add event stats: tracked, in queue, and sent counters
- Plugin status now shows Running (green), Error (red), or Available
  (gray) based on whether the plugin was successfully loaded

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: abueide

segkit/src/config_cmd.rs

@@ -18,10 +18,10 @@ fn parse_plugin_csv(raw: &str) -> BTreeSet<String> {
         .collect()
 }
 
-/// Locate and parse SegmentConfig.xcconfig from the project directory.
+/// Locate and parse SegmentConfig.conf from the project directory.
 fn load_config() -> Result<(PathBuf, XCConfig), ExitCode> {
-    let path = find_file("SegmentConfig.xcconfig").ok_or_else(|| {
-        err("No SegmentConfig.xcconfig found. Are you in a segkit project directory?");
+    let path = find_file("SegmentConfig.conf").ok_or_else(|| {
+        err("No SegmentConfig.conf found. Are you in a segkit project directory?");
         ExitCode::FAILURE
     })?;