opt no-coverage crates out of the coverage gate

cargo-coverage-gate maps any gated package that produces NO coverage data to
Verdict::ConfigError (exit 2) unless it is explicitly opted out via
`min-lines-percent = 0`. automation (script-only, entirely coverage(off)),
fundle (macro re-exports + marker structs + trait defs, no executable bodies),
and testing_aids (whole crate coverage(off)) all legitimately produce no data,
so the full-workspace gate failed even though every measured package passed.

Add `[package.metadata.coverage-gate] min-lines-percent = 0` to the three so
the gate treats their NO DATA as OK. This is also the marker anvil-llvm-cov's
impact-scoping uses to drop opted-out packages from the measured set.

With this, `cargo coverage-gate` over the per-config lcovs reports "all packages
meet their threshold" (exit 0).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: martin-kolinek

crates/automation/Cargo.toml

@@ -20,6 +20,13 @@ publish = false
 # ohno/serde/etc.
 allowed_external_types = ["*"]
 
+# Script-only crate: its entry points are `#![cfg_attr(coverage_nightly,
+# coverage(off))]`, so it produces no coverage data. Opt out of the gate
+# (min-lines-percent = 0 -> the gate treats NO DATA as OK rather than a config
+# error).
+[package.metadata.coverage-gate]
+min-lines-percent = 0
+
 [dependencies]
 
 duct = { workspace = true }

crates/fundle/Cargo.toml

@@ -20,6 +20,11 @@ repository = "https://github.com/microsoft/oxidizer/tree/main/crates/fundle"
 [package.metadata.cargo_check_external_types]
 allowed_external_types = ["fundle_macros::*"]
 
+# Facade crate: only macro re-exports, marker structs, and trait definitions --
+# no executable bodies, so it produces no coverage data. Opt out of the gate.
+[package.metadata.coverage-gate]
+min-lines-percent = 0
+
 [package.metadata.docs.rs]
 all-features = true
 

crates/testing_aids/Cargo.toml

@@ -22,6 +22,12 @@ include = { workspace = true }
 # opentelemetry/tracing/etc.
 allowed_external_types = ["*"]
 
+# Test-helper crate: the whole crate is `#![cfg_attr(coverage_nightly,
+# coverage(off))]` (its utilities are exercised opportunistically by other
+# crates' tests), so it produces no coverage data. Opt out of the gate.
+[package.metadata.coverage-gate]
+min-lines-percent = 0
+
 [dependencies]
 futures = { workspace = true, features = ["executor"] }
 opentelemetry = { workspace = true, features = ["metrics"] }