Add command line support for global variables

[Copilot]

Global variables in taskflows currently require editing YAML files. This adds -g/--global KEY=VALUE CLI arguments to set or override globals without file modifications.

Changes

CLI parsing (__main__.py)

• Added -g/--global argument (repeatable) to parse_prompt_args()
• Returns parsed globals as dictionary
• CLI globals override file-based globals via dict merge

Tests

• Added 5 test cases covering single/multiple globals, special characters, file-based globals

Documentation

• Updated README.md and GRAMMAR.md with usage examples

Usage

# Override file-based global
hatch run main -t examples.taskflows.example_globals -g fruit=apples

# Set multiple globals
hatch run main -t example -g var1=value1 -g var2=value2

# Works with Docker
docker/run.sh -t example_globals -g fruit=apples

Taskflow prompts use the same {{ GLOBALS_key }} syntax. CLI values take precedence over file values when keys match.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Globals on the command line</issue_title>
<issue_description>Currently, the only way to set a global is by editing a taskflow file. Until we implement parameter passing, it'll be useful if we set global variables on the command line.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Globals on the command line #86

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[kevinbackhouse]

@p- @m-y-mo: The way that it's currently implemented, any global values that are set in the taskflow will get overridden by the values provided on the command line. Are you happy with that design?

[m-y-mo]

yea I think it makes sense to overwrite with command line input.