v1.50.0

Model routing — role-based, deterministic, and lint-enforced

Routing was inherited from the session model (default Opus), so every implementation engineer, QA, docs, diagrams, and the Bug Council silently ran on Opus. This pins each agent to the right tier so cost savings are the default without dropping review/diagnosis quality.

• Sonnet (pinned): backend-/frontend-/mobile-/data-/devops-engineer, qa-engineer, diagrams, technical-writer. data-/devops-engineer are hybrid — destructive/irreversible migration or infra change escalates to Opus + the mandatory security-veto.
• Opus (pinned): review panel (product-manager, architect, ui-ux-engineer, code-reviewer, security-reviewer) + the gated Bug Council ×5 (was inherit).
• Haiku: fast-ops only (unchanged).
• lint-agents.sh now enforces all three tiers — CI fails if a tier silently regresses.
• Escalation policy documented (README + orchestration skill): per-dispatch model: opus override on architecture / security / prod-deploy / destructive-infra-DB / complex-root-cause / release-blocker / repeated-test-failure / unclear-requirements triggers, and FULL: lifts builders to Opus.

Gates: lint-agents.sh PASS · validate.sh PASS (CI green on #20).

Full diff: #20