feat: Vestige v1.5.0 — Cognitive Engine, memory dreaming, graph exploration, predictive retrieval

28-module CognitiveEngine with full neuroscience pipeline on every tool call.
FSRS-6 now fully automatic: periodic consolidation (6h timer + inline every
100 tool calls), real retrievability formula, episodic-to-semantic auto-merge,
cross-memory reinforcement, Park et al. triple retrieval scoring, ACT-R
base-level activation, personalized w20 optimization.

New tools (19 → 23):
- dream: memory consolidation via replay, discovers hidden connections
- explore_connections: graph traversal (chain, associations, bridges)
- predict: proactive retrieval based on context and activity patterns
- restore: memory restore from JSON backups

All existing tools upgraded with cognitive pre/post processing pipelines.
33 files changed, ~4,100 lines added.

crates/vestige-core/src/fsrs/mod.rs

@@ -52,4 +52,4 @@ pub use scheduler::{
     FSRSParameters, FSRSScheduler, FSRSState, LearningState, PreviewResults, Rating, ReviewResult,
 };
 
-pub use optimizer::FSRSOptimizer;
+pub use optimizer::{FSRSOptimizer, ReviewLog};