Follow-up to PR #11971. Documents the new code_execution.mode config
key and what each mode actually does.
- user-guide/configuration.md: add mode: project to the yaml example,
explain project vs strict and call out that security invariants are
identical across modes.
- user-guide/features/code-execution.md: new 'Execution Mode' section
with a comparison table and usage guidance; update the 'temporary
directory' note so it reflects that script.py runs in the session
CWD in project mode (staging dir stays on PYTHONPATH for imports);
drop stale 'sandboxed' framing from the intro and skill-passthrough
paragraph.
- getting-started/learning-path.md: update the one-line Code Execution
summary to match (no longer 'sandboxed environments' — the default
runs in the session's real working directory).
No code changes.
Add a hands-on guide for using voice mode with Hermes, fix and expand the main voice-mode docs, surface /voice in messaging docs, and improve discoverability from the homepage and learning path.
