Add temporalctx start/stop with optional overmind mode

[bicabone]

Summary

Adds local dev server lifecycle commands to temporalctx with optional Overmind integration.

What changed

• Added temporalctx start and temporalctx stop.
• Added tctx alias for temporalctx.
• Added plugin Procfile with temporal server start-dev.
• Start/stop behavior:
  • If overmind is installed: use Overmind (recommended) with socket at ~/.temporal/overmind.sock.
  • If overmind is not installed: use direct PID mode with ~/.temporal/temporal-dev-server.pid.
• Added --no-overmind flag for start/stop to force PID mode even when Overmind is installed.
• Updated README docs for optional/recommended Overmind behavior.
• Added tests for:
  • tctx alias
  • PID-based start/stop lifecycle
  • Overmind path
  • --no-overmind fallback

Validation

• ./tests/run.sh passes locally.