Deepen ecosystem lane environments

[forhappy]

Summary

• deepen built-in environment support for Go workspaces, Yarn Classic, Bun, uv projects, modern CMake, and approved Node lifecycle/native-addon builds
• add protocol-v2 example packages and canonical A → B → C qualification for Bazel, Gradle, Maven, and Nix
• expose exact adapter implementation/distribution identity across Rust, CLI JSON, HTTP/OpenAPI, MCP, and the SDK
• harden managed Cargo reuse by removing inherited host build-policy overrides before applying the lane's pinned policy
• make hosted qualification provision exact manager versions, prewarm every resolved uv-project cache, and derive evidence semantics from authoritative adapter plans
• fix macOS NFS/direct-private real-tool gates and portable deterministic certification evidence verification

Why

Trail recognized several ecosystems but did not have production-grade, framework-specific identity, isolation, invalidation, and real-repository handoff evidence. Cargo target seeds could also become unusable when parent-process profile or Rust flag variables changed Cargo fingerprints between construction and lane execution.

Impact

Compatible lanes reuse correctness-neutral caches and immutable seeds while retaining independent writable build state. Unsupported or unsafe variants remain fail-closed. uv-backed Python projects use source-sensitive private identities even when the qualification label is generic Python. Documentation distinguishes local qualification from hosted certification and makes no cross-platform promotion claim without a passing owning-platform gate.

Validation

Passed locally:

• cargo fmt --all -- --check
• cargo check --workspace --locked
• cargo test --workspace --locked, including 933 Trail library tests, 230 e2e tests, environment lifecycle/inheritance/fault/recovery suites, and SDK tests
• cargo clippy --workspace --all-targets --all-features --locked -- -D warnings
• 25 focused framework/external certification-verifier tests
• canonical local A → B → C evidence for uv-backed Python and external Bazel, Gradle, Maven, Nix, and Node native-addon packages
• macOS NFS Cargo seed reuse, framework isolation, recovery, Git locality, and eight-stage native artifact COW matrix
• openspec validate deepen-ecosystem-environments --strict with all 42 tasks complete

Passed hosted on implementation commit 831cd1f:

• explicit layered-workspaces certification run: all common Windows/Linux/macOS, NFS/FUSE, sandbox, adapter, cache, Node isolation, and artifact gates
• all ten real-framework A → B → C qualifications: Go, Go workspace, Yarn, Bun, pnpm, npm, Python, uv, CMake, and modern CMake
• all ten downloaded trail.ecosystem-certification/v1 artifacts re-verified locally against their authoritative raw reports

The final bfea59b commit changes only the completed OpenSpec task checkbox; fresh PR checks run on that final head.