Plan integration 1: Centralize reads and activation

[NetDevAutomate]

Parent

• Integrate Study Plans across Now, Web architect, and MCP #7 — Integrate Study Plans across Now, Web architect, and MCP

What to build

Introduce the shared PlanApplication seam through a complete first slice: immutable plan reads and consistent readiness-gated activation from CLI and Web.

Acceptance criteria

• Plan summaries and details are returned as immutable, serialization-ready views.
• CLI and Web list, inspect, and activation paths use PlanApplication.
• Create-and-activate, lifecycle activation, and imported active documents enforce identical readiness rules.
• Markdown remains authoritative and index refresh remains best-effort and recoverable.
• Domain failures contain no CLI, HTTP, or MCP types.

Blocked by

• None (can start immediately).

Definition of Done

• Existing plan behavior remains backward-compatible outside the readiness bypass being closed.
• Application-interface and cross-surface activation parity tests pass.
• Relevant existing CLI and Web plan tests pass.
• Normative capability specs and public behavior documentation are updated.
• The working tree contains no temporary artifacts and focused quality checks are green.