chore: update CLAUDE.md docs for commit signing and i18n rules

core/CLAUDE.md

@@ -22,7 +22,7 @@ cd sdk && make baseDist dist               # Rebuild SDK after ts-bindings
 - Always run `cargo check -p start-os` after modifying Rust code
 - When adding RPC endpoints, follow the patterns in [rpc-toolkit.md](rpc-toolkit.md)
 - When modifying `#[ts(export)]` types, regenerate bindings and rebuild the SDK (see [ARCHITECTURE.md](../ARCHITECTURE.md#build-pipeline))
-- When adding i18n keys, add all 5 locales in `core/locales/i18n.yaml` (see [i18n-patterns.md](i18n-patterns.md))
+- **i18n is mandatory** — any user-facing string must go in `core/locales/i18n.yaml` with all 5 locales (`en_US`, `de_DE`, `es_ES`, `fr_FR`, `pl_PL`). This includes CLI subcommand descriptions (`about.<name>`), CLI arg help (`help.arg.<name>`), error messages (`error.<name>`), notifications, setup messages, and any other text shown to users. Entries are alphabetically ordered within their section. See [i18n-patterns.md](i18n-patterns.md)
 - When using DB watches, follow the `TypedDbWatch<T>` patterns in [patchdb.md](patchdb.md)
 - **Always use `.invoke(ErrorKind::...)` instead of `.status()` when running CLI commands** via `tokio::process::Command`. The `Invoke` trait (from `crate::util::Invoke`) captures stdout/stderr and checks exit codes properly. Using `.status()` leaks stderr directly to system logs, creating noise. For check-then-act patterns (e.g. `iptables -C`), use `.invoke(...).await.is_ok()` / `.is_err()` instead of `.status().await.map_or(false, |s| s.success())`.
 - Always use file utils in util::io instead of tokio::fs when available