feat: align conformance parity and complete binary matrix

[lucarlig]

Summary

• rename routed workflow lanes to built-in-data-plane and external-data-plane
• match the Python conformance job runtime: /servers/{id}/mcp, an ephemeral unscoped catalog token, RUST_MCP_MODE=off, rate limiting disabled, one Gunicorn worker, and no-Rust control-plane build args
• keep setup and runner output in artifact logs while showing the same Braille progress UI, without dotted result leaders
• require the Rust backend marker only for the external data-plane route
• clear prior harness stacks before starting the fresh conformance sequence
• publish x86-64 and ARM64 binaries for Linux, macOS, and Windows
• build each explicit Rust target and smoke-test its native binary before packaging

Release targets

• x86_64-unknown-linux-gnu
• aarch64-unknown-linux-gnu
• x86_64-apple-darwin
• aarch64-apple-darwin
• x86_64-pc-windows-msvc
• aarch64-pc-windows-msvc

Verification

• cargo test --workspace --all-targets (316 passed)
• cargo clippy --workspace --all-targets -- -D warnings
• cargo fmt --all --check
• cargo metadata --locked --no-deps --format-version 1
• actionlint .github/workflows/release.yml
• cargo build --release --locked --bin cf-integration --target aarch64-apple-darwin
• native ARM64 macOS binary help smoke test
• release archive contents and SHA-256 verification
• exercised both routed lanes against IBM/mcp-context-forge PR 6391 at a6656afec832106ab408f64718169aaa2f92c4c9 and the published ghcr.io/contextforge-org/contextforge-data-plane:latest image
  • built-in route: 22 passed, 10 failed, 1 skipped on the raw unsuppressed 2025-11-25 suite
  • external route: 6 passed, 27 failed; the published image currently reports Fan out not supported at the moment for catalog fan-out

Stacked on #5.

[Lang-Akshay]

LGTM