feat: improved plan quality contract

[robertotru]

What

Added the first plan-quality gate so Boundline can stop unsafe execution handoff when a plan is missing a credible validation strategy. The release also persists and projects plan-quality state, findings, and accepted assumptions through status, inspect, trace, and assistant planning surfaces.

Why

This change closes the gap between planning and execution: a plan should not advance unless it has enough validation detail to prove the work can be verified. It also makes the runtime decision visible and recoverable so operators can inspect why a plan was blocked and resume cleanly after clarification.

How

• Introduced typed plan-quality state and finding/assumption models in the runtime domain.
• Evaluated plan quality only after goal quality is satisfied and before execution handoff.
• Emitted exactly one actionable clarification request when validation strategy is missing.
• Persisted additive plan-quality fields through session state, status, orchestration, inspect, and trace projections.
• Updated assistant planning assets and release-facing docs/metadata to match the new planning-readiness contract.

Validation

• cargo fmt --check
• cargo clippy --workspace --all-targets --all-features -- -D warnings
• cargo test
• cargo llvm-cov --workspace --all-features --lcov --output-path lcov.info
• scripts/common/coverage/intersect_patch_coverage.py against the changed implementation files

Checklist

• The change is scoped to one real problem and avoids unrelated cleanup.
• I updated docs, specs, or release-facing surfaces when behavior changed.
• I ran the relevant validation for the surfaces I touched.
• If I touched install, packaging, or release behavior, I kept those surfaces aligned.
• If I touched assistant command packs or compatibility guidance, I validated those paths too.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.5% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 97.28682% with 7 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/cli/orchestrate.rs	94.11%	3 Missing ⚠️
...c/orchestrator/session_runtime_native_goal_plan.rs	91.66%	2 Missing ⚠️
...c/orchestrator/session_runtime_planning_runtime.rs	98.07%	2 Missing ⚠️

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