feat: add mastery-driven Tutor progression

[ttbombadil]

Summary

Implements the mastery-driven Tutor progression contract from the approved SSOT at fdd641bbae30ceae8347f9835620c3d1274462d9.

• Adds strict Tutor manifest v2 and Curriculum Topic v2 support while preserving v1 behavior.
• Adds deterministic LEARN, DEEPEN, and EXPAND progression with explicit Topic mastery-domain classification.
• Preserves multi-topic precedence, unresolved content-exhaustion blocking, fact-inapplicability mastery retention, and revision/session reset boundaries.
• Adds phase-strategy precedence and validated expansion-target handoff.
• Carries progression metadata through the existing Tutor API/dialog history without exposing answer evidence.
• Keeps free Tutor fallback and existing revision/session authority intact.

Final review fixes

Final review fixes are included through 9315f55d9298873cbdda1e70d70fc32006069aac:

• Tutor progression is request-transactional/copy-on-write; provider errors and invalid payloads do not persist progression mutations.
• planInitial() determines the actual topic/phase before effective strategy resolution, preventing stale EXPAND strategy leakage after topic changes.
• EXPAND questions use the selected objective in the final user-visible question while keeping target-topic activation matcher-driven.
• EXPAND preserves the one-primary-question contract with exactly one final question mark.
• Regression coverage verifies failed LEARN/DEEPEN/EXPAND turns, dialog transactions, strategy/topic alignment, objective realization, and one-question output.

Validation

• Unit: 233 files, 2415 passed, 1 skipped.
• Integration: 3 files, 13 passed, 1 skipped.
• Playwright: 25 passed; no race-condition events.
• Coverage: 83.44% statements, 72.84% branches, 84.44% functions, 85.64% lines.
• Sonar Quality Gate: PASSED; new coverage 81.7%, new violations 0, bugs 0, vulnerabilities 0, security hotspots reviewed 100%, unresolved issues 0.
• Build, TypeScript check, documentation check, and diff check passed.
• Hosted CI run 36315744897: Clean-room reproducibility, Lint & Unit Tests, Arduino Toolchain Integration, Docker Sandbox Integration, and Playwright E2E all passed.

Docker/Capacity load testing was not rerun locally because Capacity and Docker behavior were not changed; the hosted Docker Sandbox Integration job passed.

Scope protections

Capacity implementation/defaults, Tutor Registry SSOT, the external UnoSim-Examples repository, and its pilot worktree were not modified.

Single-backend limitation remains: progression state is attached to the existing process-local opaque Course Content session with its current one-hour TTL; distributed session state is outside this Stage-A scope.