build: no debug info in a default build profile #8

The shared Rust rules require that no default Cargo profile carries debug info (Debug Info Is Not A Default, added in tensor4all/tensor4all-agent-rules#18).

Finding

The workspace root Cargo.toml (crate computegraph, with a trailing [workspace]) declares no [profile.*], so it builds dev/test with Cargo's default debug = 2.

Evidence: Cargo.toml @ 594cdcec60cf

Why it matters

debug = 0 is not Cargo's default for dev/test: without it the dev profile uses debug = 2, so every local cargo build, cargo test and cargo nextest run emits DWARF. Neither command reads it, and DWARF -- not code -- is what makes build output large. Measured on one machine: a single strided_kernel dev rlib reached 1.13 GiB, and the shared compiler cache held 320 GiB of dev-profile artifacts out of a 335 GiB store. debug = 1 and debug = "line-tables-only" are not a size compromise either: both emit DWARF.

Smallest useful correction

Add to the workspace root Cargo.toml:

[profile.dev]
debug = 0

[profile.test]
debug = 0

Keep debug-assertions, overflow-checks and incremental compilation as they are; they are unrelated to DWARF. A session that needs symbols asks for them with CARGO_PROFILE_DEV_DEBUG=2, and a workspace that needs readable backtraces for everyone adds one narrow opt-in profile (release-debug, profiling) instead of a default one. Cargo reads [profile.*] from the workspace root only, so a member's or a dependency's own profile block must not be changed for this.