Fail fast when native extension cannot load

[samuel-williams-shopify]

Summary

• replace the warning-and-continue native extension load with a bare require
• surface Ruby_Coverage load failures immediately as LoadError instead of later NameError failures

Tests

• PATH=/Users/samuel/.local/state/tec/profiles/base/current/global/bin:/nix/store/6nxn7dgl1556knvhjgsj1wyr87avsbq3-codex-0.138.0/lib/codex/node_modules/.pnpm/@openai+codex@0.138.0-darwin-arm64/node_modules/@openai/codex/vendor/aarch64-apple-darwin/codex-path:/nix/store/6nxn7dgl1556knvhjgsj1wyr87avsbq3-codex-0.138.0/lib/codex/node_modules/.pnpm/@openai+codex@0.138.0-darwin-arm64/node_modules/@openai/codex/vendor/aarch64-apple-darwin/codex-path:/Users/samuel/.codex/tmp/arg0/codex-arg0Bl5eV8:/nix/store/6nxn7dgl1556knvhjgsj1wyr87avsbq3-codex-0.138.0/bin:/Users/samuel/.local/state/tec/profiles/base/current/global/share/dev/bin/user:/Users/samuel/.local/state/tec/profiles/base/current/global/bin:/opt/dev/bin/user:/nix/var/nix/profiles/default/bin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/opt/pmk/env/global/bin:/Library/Apple/usr/bin bundle exec bake test
• 23 passed out of 23 total