feat(wctt): per-stream WCTT analysis pass (Track D commit 4/6)

[avrabe]

Summary

Track D commit 4/6 (of 6 for v0.8.0): wires together the network graph extraction (commit 2) and NC primitives (commit 3) into a new spar-analysis::WcttAnalysis pass that walks extracted streams and composes per-hop delay bounds end-to-end.

• Phase 1 scope (this commit): classical FIFO + Priority switches with closed-form residual-service splitting from spar-network::curves. Streams are inferred from AADL data-port connections that bind to one or more switched buses via Deployment_Properties::Actual_Connection_Binding. Per-stream end-to-end WCTT = sum of per-hop delays.
• Deferred: TSN-shaped service curves (TAS/CBS/preemption) land in Phase 2 alongside the Spar_TSN property set. latency.rs integration is the closeout commit 6. Lean theorems are commit 5.
• New AADL property: Spar_Network::WCTT_Budget (Time). Predeclared-property total goes 120 -> 121 (Spar_Network grew by 1).

What's new

• crates/spar-analysis/src/wctt.rs — new pass with 10 unit tests covering: non-regression (zero Wctt* on unswitched models), single-hop / multi-hop chain bounds, two-stream residual-service split, competing-flow exhaustion, budget exceed/within, Priority switch (treated like FIFO in Phase 1), TSN switch deferral, unannotated bus skip.
• crates/spar-analysis/tests/fixtures/wctt/classical_ethernet.aadl + .expected.json snapshot, driven by tests/wctt_fixtures.rs.
• New diagnostics: WcttBound (Info per stream), WcttExceedsBudget (Error), WcttUnservable (Error), WcttSwitchOverloaded (Error), WcttDeferred (Info Phase-2 note).
• Spar_Network grew by 1 property (WCTT_Budget => Time); per-set test bumped 4 -> 5; total-count test bumped to 121 reconciled with the v0.7.1 PIP/PCP additions already on main.
• register_all count bumped 29 -> 30.
• Rivet artefacts: REQ-NETWORK-006 (per-stream WCTT analysis) appended to requirements.yaml; TEST-WCTT linked to REQ-NETWORK-{004,005,006} appended to verification.yaml.

Test plan

• cargo build --workspace clean
• cargo test -p spar-analysis — 824 lib + 3 rta_fixtures + 1 wctt_fixtures pass
• cargo test -p spar-network — 26 lib + 6 integration pass
• cargo test -p spar-hir-def — 448 lib pass (including the bumped property-count assertion)
• cargo clippy --workspace --all-targets -- -D warnings clean
• cargo fmt --all -- --check clean
• rivet validate PASS

Out of scope

• TSN-shaped service curves (Phase 2)
• latency.rs integration with WctttCache (commit 6)
• Lean theorems for the headline NC bounds (commit 5)
• Hierarchical RTA / Track A surfaces

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 94.26606% with 50 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/spar-analysis/src/wctt.rs	94.22%	50 Missing ⚠️

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