Log configuration errors instead of silently discarding them

[ChristianPavilonis]

Summary

• Fix five sites where configuration and backend-setup errors were silently converted to None via .ok(), making broken configs appear as "not configured" with no operator feedback.
• Prebid and NextJS build() functions now use match to log deserialization failures at log::error! level before returning None.
• AdServer Mock, APS, and Prebid backend_name() methods now use .inspect_err() to log URL parsing errors before converting to Option.

Changes

File	Change
crates/common/src/integrations/prebid.rs	build(): replaced .ok().flatten()? with match + log::error!; backend_name(): added .inspect_err() before .ok()
crates/common/src/integrations/nextjs/mod.rs	build(): replaced .ok().flatten()? with match + log::error!
crates/common/src/integrations/adserver_mock.rs	backend_name(): added .inspect_err() before .ok()
crates/common/src/integrations/aps.rs	backend_name(): added .inspect_err() before .ok()

Closes

Closes #408

Test plan

• cargo test --workspace
• cargo clippy --all-targets --all-features -- -D warnings
• cargo fmt --all -- --check
• JS tests: cd crates/js/lib && npx vitest run
• JS format: cd crates/js/lib && npm run format
• Docs format: cd docs && npm run format
• WASM build: cargo build --bin trusted-server-fastly --release --target wasm32-wasip1
• Manual testing via fastly compute serve

Checklist

• Changes follow CLAUDE.md conventions
• No unwrap() in production code — use expect("should ...")
• Uses log macros (not println!)
• New code has tests
• No secrets or credentials committed

[prk-Jr]

Summary

This change fixes the five targeted silent .ok() conversions and materially improves operator visibility for config parse / backend resolution failures. I didn't find any blocking correctness issues, but I am leaving one cross-cutting follow-up about when provider endpoint validation runs.

Non-blocking

🤔 thinking

• Lazy backend validation still defers invalid endpoint detection to live traffic: backend_name() is only queried from the auction loop, so invalid endpoints are still invisible at startup and will emit one error per auction request instead of a single registration-time failure. Consider validating BackendConfig::from_url(...) during provider registration and skipping registration on failure. (crates/common/src/integrations/adserver_mock.rs:372, crates/common/src/integrations/aps.rs:520, crates/common/src/integrations/prebid.rs:954, crates/common/src/auction/orchestrator.rs:238)

CI Status

• Analyze (actions): PASS
• Analyze (javascript-typescript): PASS
• Analyze (rust): PASS
• CodeQL: PASS
• cargo fmt: PASS
• cargo test: PASS
• format-docs: PASS
• format-typescript: PASS
• vitest: PASS

[aram356]

👍 Looks good