feat: Braille spinner, shell completions, TUI polish

- Add with_spinner context manager with cyan Braille animation for human mode.
- Wrap all query/execution commands in cli.py with loading spinners.
- Integrate shtab: auto-install shell completions during init for zsh/bash.
- Add `completion` subcommand for manual script generation.
- Fix stale output_format default in DEFAULT_CONFIG.
- Add help descriptions to all second-level subcommands.
- Bump version to 2.0.5.

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 = "2.0.4"
+version = "2.0.5"
 description = "Binance-first trading CLI for balances, market data, opportunity scanning, and execution."
 readme = "README.md"
 license = {text = "MIT"}