test(self-managed): HA profile validation - single-node compatibility and failure tests

Description

Validate highAvailability profiles end-to-end:

1. Single-node / local BDD — profile: single-node (or HA disabled) must keep laptop/CI installs working (replicas=1, no hard anti-affinity that leaves pods Pending).
2. MVP failure tests on ≥3 nodes — production profile must meet basic resilience acceptance (install shape, Tier-1 pod kill, node drain).

Definition of Done

• Local k3d / BDD path still installs successfully with single-node (or HA off)
• tests/bdd/fixtures/self-managed-local-bdd.yaml (or equivalent) remains compatible
• Production-profile install on ≥3 nodes: Tier-1 ≥2 Ready; Tier-2 = 3 Ready
• Tier-1 pod kill in one AZ: invocations still succeed
• kubectl drain of one node: PDB enforced; service remains available
• Results/instructions checked into the repo or linked from the epic
• Documented that single-node is local/dev only, not production HA

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