pub fn write_project_pin(root: &Path, pin: &ProjectPin) -> Result<PathBuf>Expand description
Write a palace pin to .trusty-tools/trusty-memory.yaml at root.
Why: the lazy-write path in project_slug_at and the explicit
trusty-memory link backfill command both need to emit the same YAML
schema. A single writer keeps the format consistent and avoids duplicated
YAML-construction logic.
What: creates .trusty-tools/ if missing, serialises pin with
serde_yaml, and writes it atomically (write to <file>.tmp, then
rename). Returns the path that was written.
Test: write_project_pin_creates_expected_yaml,
write_project_pin_round_trips_through_read.