Add support for stable environment fingerprinting and session reproducibility tags

[pugsley76]

Description:
Glassbox should fingerprint the runtime environment and include it in session metadata for reproducibility.

Work to be done:
Generate a stable environment fingerprint from CLI version, OS, and relevant dependency versions.

Implementation procedure:

1. Define the fields used for environment fingerprinting.
2. Add fingerprint generation during session creation.
3. Store the fingerprint in session metadata and exports.
4. Add tests for fingerprint stability.
5. Document the fingerprint fields.

Acceptance criteria:

• Session metadata includes a stable environment fingerprint.
• Fingerprint fields are documented.
• Tests verify stability across the same environment.
• Documentation explains the fingerprint purpose.

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