[Feature]: Add Support for Custom Headers via CLI Flags

[dinocodesx]

Describe the feature you are requesting

Currently, Termino-Logistic allows users to specify request headers only within YAML/JSON configuration files. However, there is no way to define headers dynamically via command-line arguments.

💡 Proposed Feature:

• Enable users to pass HTTP headers via CLI flags using the -H or --header option.
• Allow multiple headers to be defined using the flag multiple times.
• Ensure that CLI-defined headers override headers set in the request file (if there’s a conflict).

📝 Example Usage:

# Sending a GET request with custom headers
termino -f request.yml -H "Authorization: Bearer mytoken" -H "User-Agent: CustomClient/1.0"

Why is this feature needed?

• Improves flexibility by allowing users to quickly modify headers without editing configuration files.
• Useful for authentication (e.g., API keys, JWT tokens) where tokens may change frequently.
• Enhances debugging and testing, as users can quickly test API responses with different headers.

---

Implementation Plan

1️⃣ Modify Argument Parser (main.py)

Update parse_args() in main.py to accept custom headers as CLI arguments:

ap.add_argument(
    "-H", "--header",
    action="append",
    help="Specify custom HTTP headers (use multiple times for multiple headers)"
)

This allows users to pass -H "Key: Value" multiple times.

2️⃣ Process Headers in Yeeter (feet.py)

Modify the yeet() method to:

• Parse CLI headers into a dictionary.
• Merge CLI headers with request file headers (CLI headers take precedence).

3️⃣ Update Help Documentation in README.md

• Add an example of how to use the -H flag.
• Clarify that CLI headers override request file headers if duplicated.

---

Additional Context

• 🚀 This feature aligns with industry-standard CLI tools like curl, enhancing usability.
• 🔥 Good First Issue for contributors familiar with Python, argparse, and API requests.

Would love feedback on the design! Feel free to contribute. 😃