Full Windows support

[Archmonger]

Description

This PR adds full Windows compatibility to the django-dbbackup package by implementing comprehensive cross-platform support across the test suite and core functionality.

• Replaces hardcoded Unix paths (/tmp) with repository-local temporary directories for better cross-platform compatibility
• Adds GPG availability detection and conditional test skipping to handle environments where GPG is not installed
• Implements Windows-specific fixes for SQLite backup temporary file handling to resolve file locking issues

Checklist

Please update this checklist as you complete each item:

• Tests have been developed for bug fixes or new functionality.
• The changelog has been updated, if necessary.
• Documentation has been updated, if necessary.
• GitHub Issues closed by this PR have been linked.

_{By submitting this pull request I agree that all contributions comply with this project's open source license(s).}

[Copilot]

Pull Request Overview

This PR adds full Windows compatibility to the django-dbbackup package by implementing comprehensive cross-platform support across the test suite and core functionality.

• Replaces hardcoded Unix paths (/tmp) with repository-local temporary directories for better cross-platform compatibility
• Adds GPG availability detection and conditional test skipping to handle environments where GPG is not installed
• Implements Windows-specific fixes for SQLite backup temporary file handling to resolve file locking issues

Reviewed Changes

Copilot reviewed 18 out of 19 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/utils.py	Updates TEST_DATABASE path to use repository-local tmp directory instead of /tmp
tests/test_utils.py	Adds GPG availability detection and conditional test skipping for encryption tests
tests/test_storage.py	Changes storage location from /tmp to tmp for cross-platform compatibility
tests/settings.py	Replaces system temporary directories with repository-local tmp directory
tests/functional/test_commands.py	Adds GPG availability checks and conditional test skipping
tests/commands/test_mediabackup.py	Implements GPG availability detection for encryption tests
tests/commands/test_dbrestore.py	Adds GPG availability checks for decryption tests
tests/commands/test_dbbackup.py	Updates file paths to use repository-local tmp directory
tests/commands/test_base.py	Changes test file paths from /tmp to repository-local tmp directory
pyproject.toml	Updates functional test environment to use relative paths instead of /tmp
docs/src/configuration.md	Adds Windows-specific documentation for GPG requirements
docs/src/commands.md	Updates example output paths to reflect new temporary directory structure
dbbackup/db/sqlite.py	Implements Windows-compatible SQLite backup with proper temporary file handling
dbbackup/db/base.py	Adds Windows compatibility for command execution with builtin POSIX utility shims
CHANGELOG.md	Documents Windows compatibility improvements and SQLite fixes
.github/workflows/ci.yml	Extends CI matrix to include Windows testing
.github/copilot-instructions.md	Updates development instructions to reflect new tmp directory structure
.editorconfig	Adds editor configuration for consistent formatting across platforms