plex browser sign-in auth, log viewer

[tonywied17]

This pull request introduces improvements to logging configuration and documentation, and adds a new Plex browser PIN sign-in flow. The most important changes are the addition of a log_append option for controlling log file behavior, enhancements to the logger implementation, and detailed updates to the documentation, including instructions for the new Plex sign-in flow.

Logging configuration and implementation:

• Added a log_append setting to config.json, Config, and logger setup, allowing users to choose whether logs are appended or overwritten on startup. The logger now respects this setting both in CLI and GUI modes. (config.json, src/core/config.py, src/core/logger.py, src/ui/cli/app.py) [1] [2] [3] [4] [5]
• Improved logger handler management to preserve custom handlers and avoid duplicates, and added stacklevel=2 to log methods for better source tracing. (src/core/logger.py) [1] [2]
• Updated log file behavior documentation and usage in the GUI, including the Log Viewer and troubleshooting sections. (README.md) [1] [2] [3]

Plex authentication enhancements:

• Added a new plex_auth_service.py module implementing the Plex browser PIN (TV-code) sign-in flow, including functions for PIN creation, browser opening, and polling for authentication token. (src/services/plex_auth_service.py)
• Updated documentation to describe the new Plex sign-in flow, including instructions, troubleshooting, and integration with the GUI. (README.md) [1] [2]

Documentation improvements:

• Added badges, a structured table of contents, and clarified advanced features and settings in README.md. (README.md) [1] [2] [3]

Minor improvements:

• Changed a print statement to a logger info call in the GUI scrape handler for consistency. (src/ui/gui/handlers/scrape_handler.py)