docs/test(deploy): composition-modes doctrine + cross-mode conformance suite [SD-7]

[rickylabs]

Part of #830 (gap G7 — the anti-fork enforcement). One reference app runs in BOTH composition modes; the suite asserts the seven shared rows (transport, discovery, data layout, packaging pipeline, release/update, provisioning, telemetry identity). Plus the composition-modes doctrine entry (mode selection rule).

Depends on: #451, #454, #456, #832, #831, #834, #835.

• gate: conformance suite green in both modes; doc:lint

Design source: PR #822 (rfc.md + plan.md rev 10, 9-cycle adversarial trail) in .llm/runs/rfc-single-deployment--orchestrator/. (plan.md §D)