Add direct Tinybird auction telemetry

[ChristianPavilonis]

Summary

• Adds direct, best-effort Tinybird Events API ingestion for auction telemetry from Fastly Compute.
• Introduces privacy-preserving core auction telemetry rows plus a Fastly fire-and-forget sink using Secret Store APPEND tokens.
• Adds Tinybird datasources, rollups, endpoint pipes, fixtures, and YAML test contracts for Grafana-facing telemetry.

Changes

File	Change
crates/trusted-server-core/src/auction/telemetry.rs	Adds auction observation context, row model, NDJSON batching, privacy-preserving page path normalization, terminal outcomes, no-op sink, and best-effort emit helper.
crates/trusted-server-core/src/auction/endpoints.rs	Emits skipped/completed/execution-failed telemetry for POST /auction without changing response behavior.
crates/trusted-server-core/src/publisher.rs	Emits completed/skipped/dispatch-failed/abandoned telemetry for initial-navigation SSAT and SPA /__ts/page-bids paths.
crates/trusted-server-core/src/auction/orchestrator.rs	Tracks split dispatch outcomes, retained launch failures, timeout rows, and explicit abandonment metadata.
crates/trusted-server-core/src/platform/types.rs	Adds AuctionTelemetrySink plumbing to RuntimeServices.
crates/trusted-server-core/src/settings.rs, trusted-server.toml, fastly.toml	Adds disabled-by-default Tinybird config, validation, and fake local Secret Store placeholders.
crates/trusted-server-adapter-fastly/src/tinybird.rs	Adds Fastly Tinybird sink that builds NDJSON Events API POSTs, calls send_async, and drops pending responses.
crates/trusted-server-adapter-fastly/src/app.rs, src/main.rs, src/platform.rs	Wires the configured telemetry sink through EdgeZero and legacy runtime services.
tinybird/**	Adds raw/rollup datasources, materialized and endpoint pipes, fixture NDJSON, and YAML endpoint test contracts.
docs/superpowers/**	Adds revised spec and implementation plan for direct Tinybird ingestion.

Closes

Closes #817

Test plan

• cargo test --workspace
• cargo clippy --workspace --all-targets --all-features -- -D warnings
• cargo fmt --all -- --check
• JS tests: cd crates/trusted-server-js/lib && npx vitest run
• JS format: cd crates/trusted-server-js/lib && npm run format
• Docs format: cd docs && npm run format
• WASM build: cargo build --package trusted-server-adapter-fastly --release --target wasm32-wasip1
• Manual testing via fastly compute serve
• Other: cd tinybird && TB_CLI_TELEMETRY_OPTOUT=1 uvx --from tinybird-cli tb check
• Other: YAML test contract parse check with python3/yaml
• Other: git diff --check

Note: tb test run -v was attempted, but the available Tinybird CLI exited opaquely with Error: ** before executing scenarios; tb check validates the datafiles and YAML test contracts parse successfully.

Checklist

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