v0.5.0

v0.5.0 ships the engine spine and the Pillar-3 headline feature: the On-Demand Context Compiler (Phase 7), built on the Pipeline orchestrator, Supervisor daemon, and live session monitor (Phases 1-3). Phase 4 lands incremental-compile infrastructure (provenance sidecar, GraphStore delete surface; flag stays OFF/experimental), Phase 5 activates persistent self-improvement via the node_memory sidecar with numeric recurrence confidence in output and supersede default-on, and Phase 6 brings real default embeddings (Track B). Also fixes changed-only compile idempotence and the injected-store contract in project compile, adds 7-language localized docs for the context-engine audit/roadmap, and brings the test suite to 1544 passed / 0 failed.