Summary

Fixes #173. Two related bugs, one root cause:

Primary: planning graph misses optional workspace deps

build_plan in crates/shipper-core/src/plan/mod.rs constructed the workspace dependency DAG from cargo_metadata's feature-resolved resolve.nodes. That graph omits optional path+version dependencies that are not active under the default feature set. cargo publish, however, still needs every optional workspace path+version dep to be resolvable from the registry at publish time, so those edges must participate in publish ordering.

Concretely, uselesskey-aws-lc-rs declares optional normal path+version deps on uselesskey-rsa/uselesskey-ecdsa/uselesskey-ed25519. Because those edges were absent from resolve.nodes, Shipper saw uselesskey-aws-lc-rs as indegree zero, the deterministic BTreeSet<(name, id)> ready queue emitted it early by name, and the plan looked alphabetical. It was a correct topological sort of an incomplete graph.

The "publishable depends on non-publishable workspace member" guard at the same site (mod.rs:160-189) had the same defect — same iteration source.

Fix: switch both edge construction and the validation guard to manifest-level Package.dependencies. Include DependencyKind::Normal | DependencyKind::Build, including optional and target-specific deps; exclude Dev. Path deps are resolved to workspace members via a directory→PackageId map.

Not switching to cargo metadata --all-features: that would surface optional deps but couples planning to "all features build", an unrelated and expensive constraint.

Secondary: ambiguous classification on dep-resolution failures

crates/shipper-cargo-failure/src/lib.rs did not match Cargo's dep-resolution error messages, so a publish failure caused by a missing registry dep (exactly the failure mode produced by the planning bug above) fell through to Ambiguous. The retry loop then hid the actionable Cargo stderr behind a sequence of "publish outcome ambiguous; registry did not show version" retries.

Adds four permanent patterns:

• failed to select a version for the requirement
• no matching package named
• candidate versions found which didn't match
• required dependency is missing from the registry

Tests

New regression tests:

• build_plan_orders_optional_workspace_dependencies — aaa-adapter optional-depends on zzz-core. Alphabetical order is aaa-adapter, zzz-core; correct publish order is zzz-core, aaa-adapter. Fails on the prior implementation.
• build_plan_rejects_optional_normal_dep_on_non_publishable_workspace_member — same defect in the validation path.
• realworld_dep_resolution_without_verify_framing — Cargo dep-resolution stderr without the surrounding "failed to verify package tarball" framing. Misclassified as Ambiguous before this PR.
• realworld_no_matching_package_named — the package-not-found shape.

Existing 234 plan tests and 190 classifier tests continue to pass.

Validation performed locally

• cargo check --workspace --all-targets --locked — clean
• cargo clippy -p shipper-core -p shipper-cargo-failure --all-targets --locked -- -D warnings — no issues
• cargo fmt --all -- --check — clean
• cargo test -p shipper-core --lib plan:: — 236 passed (234 existing + 2 new)
• cargo test -p shipper-cargo-failure — 192 passed (190 existing + 2 new)

Snapshot permanent_pattern_exhaustive.snap updated with the four new patterns.

Test plan

• CI green.
• Spot-check that the new tests run on CI and fail without the source-side fix (i.e., that they are real regression tests).
• After merge, retry the uselesskey workspace publish that surfaced shipper publish: plan order appears alphabetical rather than topological; first-listed crate has unmet workspace deps #173 (or the smallest reproducer the user has) to confirm the plan now orders the optional deps correctly.