Add MAX_QUERY_LENGTH guard in handle_chat to prevent overly long queries (#83)

[tisha-varma]

This PR adds a configurable query length guard in handle_chat to prevent excessively long inputs from reaching the Gemini API.

Changes:

• Introduced MAX_QUERY_LENGTH environment variable (default: 2000 chars)
• Added early validation in handle_chat
• Trimmed whitespace before validation
• Added tests to verify guard behavior
• Documented MAX_QUERY_LENGTH in .env.template

This prevents token limit errors from large inputs and provides users with a clear, friendly message.

Fixes #83

[QuantumByte-01]

Correct and clean implementation. One minor nit: int(os.getenv("MAX_QUERY_LENGTH", "2000")) at module load will raise ValueError if someone sets it to a non-integer string in .env. Consider wrapping in a try/except with a fallback. Not a blocker.

[tisha-varma]

Correct and clean implementation. One minor nit: int(os.getenv("MAX_QUERY_LENGTH", "2000")) at module load will raise ValueError if someone sets it to a non-integer string in .env. Consider wrapping in a try/except with a fallback. Not a blocker.

Thank you for the suggestion. I’ve added a try/except with a fallback to the default value.