[deploy-plugin DPB-1] Move deploy contracts to plugin-deploy-core behind compatibility re-exports

[rickylabs]

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

Move DeployTargetPort/DeployOperation and the result/error types from the CLI kernel to plugin-deploy-core (./ports, ./domain) behind compatibility re-exports; fix the stale "uniform 7-op" comment to eight-op/declared-subset, including matching doctrine/gate wording. Anti-scope: no behavior change; no registry, conventions, or build-engine move (DP-2, SF-2).

Acceptance

• gate: deno task e2e:cli green with zero verb changes
• gate: consumer imports compile via the re-exports
• gate: no "7-op" wording remains in moved code or the doctrine touched by this slice

Metadata

Dependencies: none
Delivery shape: contracts extraction, no vendor work