[deploy-plugin DPB-10] Adapter-side config member schemas over the schema registry

[rickylabs]

Part of #892 (RFC #891; corpus .llm/runs/plan-deploy-plugin--seed/ r5).

Per-target config member schemas move to their adapter packages (spreading the base — R-DEPLOY-4); the deploy slice of config-plugin-specific-schema-debt retires. Anti-scope: the frozen legacy union keeps parsing all existing keys.

Acceptance

• gate: all shipped target keys parse identically (golden configs)
• gate: the config debt entry is retired with an evidence link

Metadata

Dependencies: DPB-6, DPB-7, DPB-8, DPB-9
Delivery shape: config re-home