refactor(statusline): convert fetch-rate-limits.sh to TypeScript

Consolidate all rate limit fetching logic into format-status.ts, eliminating
the separate bash script. The TypeScript file now operates in dual mode:

1. As a library (exported functions) for import by other modules
2. As a CLI (when executed directly) for the session-start.sh hook

Key improvements:
- Single language (TypeScript) instead of bash/TS hybrid
- Native fetch API (Node 18+) instead of curl + jq
- Type-safe JSON parsing with proper interfaces
- Better error handling with try/catch
- No external jq dependency

The file includes CLI mode detection at the bottom to enable JSON output
when called directly from the bash hook.

Co-Authored-By: duyetbot <duyetbot@users.noreply.github.com>

Author: claude

statusline/hooks/session-start.sh

@@ -5,8 +5,8 @@
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 PLUGIN_ROOT="$(dirname "$SCRIPT_DIR")"
 
-# Fetch rate limits
-rate_limits=$("$PLUGIN_ROOT/scripts/fetch-rate-limits.sh" 2>/dev/null)
+# Fetch rate limits using TypeScript CLI
+rate_limits=$(node --no-warnings "$PLUGIN_ROOT/scripts/format-status.ts" 2>/dev/null)
 
 # Parse rate limit values
 if [ -n "$rate_limits" ]; then