Docs: getting-started pins version 0.0.13, and "keeps undeclared files out" overstates the sandbox

[kaghni]

Two small doc mismatches found while following docs/user/getting-started.md with 0.5.0rc2.

1. Schema version in the example spec. Step 3 shows

version: "0.0.13"   # ASTRA schema version — keep what the scaffold wrote

but lc init writes version: "0.0.14" (astra-tools 0.2.17 / astra-spec 0.0.14). Pasting the block as-is downgrades the pin, which astra validate then warns about. The comment says to keep what the scaffold wrote, but the literal value contradicts it.

2. "keeps undeclared files out" is broader than the actual behaviour. The README says recipes run "under a sandbox (Landlock on Linux, Seatbelt on macOS) that keeps undeclared files out". On macOS, a recipe probe gave:

Probe	Result
read ~/.zshrc, read a sibling repo	denied
write outside the project (non-tmp)	denied
write in-tree outside the output dir	denied
read undeclared in-tree files (data/points.csv not in the output's inputs, uv.lock)	allowed
write /tmp	allowed
network	allowed

This matches sandbox/policy.py (the project root is granted read; /tmp is writable by design), so it's a wording issue, not a sandbox bug. But "undeclared files" reads as "files the output didn't declare". Suggest "keeps files outside the project out", plus a note that declaring an input is for provenance and staleness, not access control.