Migrate configuration and data location

[OwendB1]

This pull request updates Quasar's documentation and configuration to standardize the install and data root handling for both Linux and Windows deployments. The main theme is a shift from legacy, OS-specific data directories (like ~/.config/Quasar or %APPDATA%\Quasar) to using the install root directory as the default location for both installation and persistent data, unless explicitly overridden. The changes also clarify migration behavior for legacy data, update install/uninstall instructions, and improve documentation to match the new conventions.

Key changes include:

Install/Data Directory Handling and Migration:

• The default install and data root for both Linux and Windows is now the extracted installer directory, not the OS-specific app-data path. Legacy data directories are automatically migrated into the install root on first launch unless a custom QUASAR_DATA_DIR is set. [1] [2] [3] [4] [5] [6] [7]
• Documentation and reference comments updated throughout to reflect that all persistent state and configuration now default to the install root, with explicit instructions for overriding via environment variable or install flags. [1] [2]

Installation and Uninstallation Instructions:

• Linux and Windows quickstart and deployment docs now show extraction and install commands that use the install root as the default location, with clear options for customizing install/data directories. [1] [2] [3] [4] [5]
• Uninstall instructions updated to clarify that --purge removes the install/data root, not just the legacy folder. [1] [2]

Versioning:

• Project version incremented from 1.0.0 to 1.0.1 in Directory.Build.props.

These changes make Quasar's installation and persistent data handling more predictable and easier to manage, especially for users deploying on different platforms or migrating from older versions.