feat: add senior stock command

[br-monteiro]

This pull request introduces a new senior-stock command to the CLI tool, enabling users to fetch and display stock data from the Senior stock API with flexible filtering, column selection, and caching. The implementation includes robust configuration management, a file-based cache system, and comprehensive tests to ensure reliability and usability.

The most important changes are:

New Command: Senior Stock

• Added the senior-stock command (commands/senior-stock/__init__.py) that fetches and displays stock data from the Senior stock API, supporting filter expressions (exact and regex), column selection, and cache bypassing. ([commands/senior-stock/__init__.pyR1-R92](https://github.com/quinta-serie/onecli/pull/6/files#diff-f1f0cdbd401eaa2a3598ea19d73dca4baa19cd492600352d2fcf055ebbe62547R1-R92))
• Added a detailed usage and configuration guide for senior-stock in commands/senior-stock/README.md, including environment variable overrides and example invocations. ([commands/senior-stock/README.mdR1-R122](https://github.com/quinta-serie/onecli/pull/6/files#diff-a34f6a0c88561e7ee5caa6fe6bd214ef9630132ffdfc8df09b1f10f644e874d1R1-R122))
• Updated the main README.md to list the new senior-stock command and link to its documentation. ([README.mdR169-R177](https://github.com/quinta-serie/onecli/pull/6/files#diff-b335630551682c19a781afebcf4d07bf978fb1f8ac04c6bf87428ed5106870f5R169-R177))

API Integration & Caching

• Implemented SeniorStockAPI (commands/senior-stock/senior_stock_api.py) to handle authentication (with token caching and refresh), stock data retrieval (with response caching and retries), and configuration validation. ([commands/senior-stock/senior_stock_api.pyR1-R100](https://github.com/quinta-serie/onecli/pull/6/files#diff-affde435499a2527fb33164f3adb7b73f56345df95a93e524061c086e79fd962R1-R100))
• Introduced a simple, file-based cache system (common/cache.py) with optional TTL, used for both API tokens and stock data. ([common/cache.pyR1-R49](https://github.com/quinta-serie/onecli/pull/6/files#diff-edf1124cf784fc7a1708133d574fb6e1fa35b25dac8d97f5ca1c2a81e7bd91cbR1-R49))

Configuration Management

• Enhanced common/config.py to support layered configuration: settings from ~/.oneclirc can be overridden by ONECLI_* environment variables, with correct precedence and merging for command-specific settings. ([[1]](https://github.com/quinta-serie/onecli/pull/6/files#diff-1bacff878451e5aa9c6d164150c7b2daad028d5e7acba90bb720cb73ffdd827bL24-R26), [[2]](https://github.com/quinta-serie/onecli/pull/6/files#diff-1bacff878451e5aa9c6d164150c7b2daad028d5e7acba90bb720cb73ffdd827bR39-R45), [[3]](https://github.com/quinta-serie/onecli/pull/6/files#diff-1bacff878451e5aa9c6d164150c7b2daad028d5e7acba90bb720cb73ffdd827bL57-R60))

Testing

• Added comprehensive unit and integration tests for the senior-stock command, covering filter parsing, column selection, CLI argument handling, and output validation (tests/commands/senior-stock/test_command.py). ([tests/commands/senior-stock/test_command.pyR1-R294](https://github.com/quinta-serie/onecli/pull/6/files#diff-60adf3d923867f479cbe3a4d3fdb9fad06d17ea55d2fcadf53a51f20aa0bdd95R1-R294))