Step 21d/23 (Phase 6): Docs — Add Administrator's Manual Update Guide

[Jordan231111]

Summary

Add an Administrator's Manual Update Guide covering how to update Rust, Python, system dependencies, and the signature database.

Depends On: None
Parent Issue: #15 (Documentation Completion)

Context

From the Comprehensive Plan, administrators need clear instructions for keeping the tool and its dependencies up to date.

Key Changes

1. Create `docs/admin-update-guide.md` with sections:
   • Updating Rust and Cargo: `rustup update stable`, `rustup default stable`, verify with `rustc --version`
   • Updating Rust dependencies: `cargo update`, `cargo update --aggressive`, review `Cargo.lock` changes
   • Updating Python dependencies: `pip install --upgrade requests pytest rich`
   • Updating system dependencies: platform-specific commands (apt, brew, choco)
   • Manual database update: `python python_scripts/generate_signatures.py`, `gh workflow run update_signatures.yml`
   • Verifying updates: run test suite, check for deprecation warnings
2. Each section must have exact commands — no vague instructions

Acceptance Criteria

• Guide covers Rust, Python, system deps, and database updates
• All commands are exact and copy-paste ready
• Platform-specific commands are provided for Linux, macOS, Windows
• Verification steps are included after each update type
• Guide is linked from README and CONTRIBUTING docs