feat: add progression readiness api

.planning/phases/004-progression/004-CONTEXT.md

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+# Phase 4 Context: Progression
+
+**Status:** Ready for execution
+**Started:** 2026-04-26
+
+## Goal
+
+Expose visible, evidence-backed progression after diagnostic practice.
+
+## Inputs
+
+- OpenSpec `learning-progression` requirements.
+- `docs/planning/GAMIFICATION.md`.
+- Phase 3 learner memory snapshots.
+- Existing workflow contracts for `NextChallenge` and `ReadinessUpdate`.
+
+## Decisions
+
+- Derive MVP readiness directly from learner memory.
+- Keep progression read-only except for future workflow outputs.
+- Do not add streak persistence yet.
+- Rewards and unlocks must be deterministic and evidence-backed.
+
+## Boundaries
+
+In scope:
+
+- Role readiness map API.
+- Concept ladder level calculation.
+- Next challenge selection API.
+- Boss-style unlock when prerequisite concepts are stable.
+- Tests and verification.
+
+Out of scope:
+
+- Frontend map UI.
+- Persistent campaign/streak storage.
+- Social leaderboards.
+- Random reward economy.