chore(coverage): restore targeted --ignore-filename-regex for cargo-llvm-cov

#[cfg(not(tarpaulin_include))] is not recognized by cargo-llvm-cov —
it only works with cargo-tarpaulin. Restore --ignore-filename-regex
but more precisely than before: exclude only the specific runtime
orchestration files (main.rs, connection.rs, upgrade.rs, OTel modules)
while keeping config modules, service_name.rs, and test code covered.

Author: yordis

rsworkspace/.cargo/config.toml

@@ -2,5 +2,7 @@
 cov = [
     "llvm-cov",
     "--all-features",
-    "--workspace"
+    "--workspace",
+    "--ignore-filename-regex",
+    "crates/acp-nats-stdio/src/main\\.rs|crates/acp-nats-ws/src/(main|connection|upgrade)\\.rs|crates/acp-telemetry/src/(lib|signal|trace|log|metric)\\.rs"
 ]