## Why
Keep source locations available without full debug information in ordinary builds, and retain symbols until release packaging. macOS targets also need to avoid invoking `dsymutil` in Linux remote Rust actions where it is unavailable.
## What changed
- Set Cargo's `dev` profile to `line-tables-only` and let `ci-test` inherit it through `test`. Document environment overrides for full debug information.
- Patch `rules_rs` to use line tables for `fastbuild` and `opt`, full debug information for `dbg`, and no stripping in all three modes.
- Disable split debug information for macOS toolchains, matching Cargo's release policy.
GitOrigin-RevId: 9e92b28f9647cea7dd73084febd84726b1cee279
