feat: enhance pixi task add CLI command to support issue #3828

[DishankChauhan]

Summary

This PR enhances the pixi task add CLI command to address all requirements from issue #3828.

Changes Made

🔧 Enhanced CLI Features

• Enhanced dependency parsing: Support for task:env and task::arg1,arg2 formats
• Task arguments with defaults: --arg name and --arg name=default
• Inputs/outputs support: --inputs "*.rs" and --outputs "target/*"
• Alias creation: Create aliases using --depends-on without commands
• Validation: Ensures either commands or dependencies are provided

🔄 Backward Compatibility

• All existing functionality preserved
• Existing task definitions continue to work unchanged
• No breaking changes to the API

✅ Testing

• Comprehensive manual testing of all new features
• All existing tests pass
• Fixed integration test compilation
• Clippy and formatting checks pass

Example Usage

# Enhanced dependency with environment
pixi task add deploy --depends-on build:production

# Task with arguments and defaults
pixi task add compile echo "Mode: $MODE" --arg mode=debug

# Alias creation (no commands, just dependencies)
pixi task add test-all --depends-on test-unit test-integration

# With inputs and outputs
pixi task add build cargo build --inputs "src/**/*.rs" --outputs "target/debug/*"

Fixes #3828

[ruben-arts]

Great additions! It's not yet hooked up properly as i found out with the inputs and outputs. I really like the idea of the splitting you implemented on the args and depends on!

Could you add all possible new commands as an integration test?
The best location for that would be: tests/integration_python/test_main_cli.py.

[ruben-arts]

The inputs and outputs are not serialized when adding e.g.:

pixi task add test10 --inputs "*.rs" --outputs "target" echo hello

results in:

test10 = { cmd = "echo hello" }