fix: allow -a/--agent flag after subcommands

- Preprocess argv to reorder agent flag before subcommand parsing.
- Enables usage like `coinhunter account overview -s -f -a`.
- Bump version to 2.0.6.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "coinhunter"
-version = "2.0.5"
+version = "2.0.6"
 description = "Binance-first trading CLI for balances, market data, opportunity scanning, and execution."
 readme = "README.md"
 license = {text = "MIT"}