sync docs with implemented decision baseline

[shchukins]

What changed

• synced top-level and AI-context docs with the actually implemented readiness decision baseline
• updated product and UI docs to reflect existing recommendation, reason, briefing, and data_quality outputs
• corrected docs that still described recommendation / ride briefing as planned-only layers
• documented the current architectural drift risk around duplicated readiness formatting between decision_engine and legacy notification formatting

Why

Several documents had drifted behind the implementation.

The backend already exposes a deterministic decision baseline on top of readiness_daily, but parts of the docs still described that layer as planned. That creates two problems:

• product/docs overstate what is still missing
• architecture/docs understate the current duplication risk in the delivery layer

This PR brings the docs back in line with the implemented system.

Scope

Updated:

• README.md
• README.ru.md
• docs/ai/PRODUCT_CONTEXT.md
• docs/ai/CURRENT_PRIORITIES.md
• docs/ai/GLOSSARY.md
• docs/product/CURRENT_STATE.md
• docs/ui/READINESS_TODAY_SCREEN.md
• docs/architecture/OPEN_DECISIONS.md

Key clarifications

• deterministic recommendation baseline is already implemented
• deterministic ride briefing baseline is already implemented
• broader planning features remain planned:
  • duration guidance
  • calendar-aware timing
  • richer day-context planning
• subjective feedback remains a separate evaluation/calibration layer
• formatting drift between decision_engine and notification_service is now explicitly tracked as an open architecture concern

Impact

• docs now distinguish implemented baseline guidance from still-planned planning features
• AI/project context files now reflect the real backend boundary more accurately
• architectural risk is made explicit instead of being hidden by stale wording

Validation

Reviewed against current implementation in:

• backend/backend/services/decision_engine.py
• backend/backend/services/readiness_daily.py
• backend/backend/services/readiness_query.py
• backend/backend/services/notification_service.py
• backend/backend/services/subjective_feedback_service.py

Tests

• no tests run
• documentation-only changes