Implement terminal mutation and archive extraction receipts

[mdheller]

Purpose

Implement TurtleTerm support for SourceOS Mutation and Evidence Accountability, anchored to SourceOS spec PR wezterm#96:

SourceOS-Linux/sourceos-spec#96

Required behavior

TurtleTerm must emit terminal/session mutation receipts for:

• interactive shell sessions;
• command execution;
• file writes;
• archive extraction;
• chmod/chown/xattr changes;
• downloads;
• diagnostic collection;
• agent-driven terminal work.

Acceptance criteria

• Terminal session receipts include session ID, working directory path class, command class or redacted command digest, process tree, user intent class, and output artifact class.
• Archive extraction receipts include source archive class/hash, output path class, file count, byte count, permissions/xattrs, quarantine state, cleanup policy, and downstream indexing/sync candidates.
• Diagnostic commands emit observer-effect receipts when they write evidence bundles or traces.
• Tests reject archive extraction receipts with unknown path class or missing cleanup policy.