feat: Vestige v2.0.0 "Cognitive Leap" — 3D dashboard, HyDE search, WebSocket events

The biggest release in Vestige history. Complete visual and cognitive overhaul.

Dashboard:
- SvelteKit 2 + Three.js 3D neural visualization at localhost:3927/dashboard
- 7 interactive pages: Graph, Memories, Timeline, Feed, Explore, Intentions, Stats
- WebSocket event bus with 16 event types, real-time 3D animations
- Bloom post-processing, GPU instanced rendering, force-directed layout
- Dream visualization mode, FSRS retention curves, command palette (Cmd+K)
- Keyboard shortcuts, responsive mobile layout, PWA installable
- Single binary deployment via include_dir! (22MB)

Engine:
- HyDE query expansion (intent classification + 3-5 semantic variants + centroid)
- fastembed 5.11 with optional Nomic v2 MoE + Qwen3 reranker + Metal GPU
- Emotional memory module (#29)
- Criterion benchmark suite

Backend:
- Axum WebSocket at /ws with heartbeat + event broadcast
- 7 new REST endpoints for cognitive operations
- Event emission from MCP tools via shared broadcast channel
- CORS for SvelteKit dev mode

Distribution:
- GitHub issue templates (bug report, feature request)
- CHANGELOG with comprehensive v2.0 release notes
- README updated with dashboard docs, architecture diagram, comparison table

734 tests passing, zero warnings, 22MB release binary.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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

@@ -8,6 +8,7 @@
 //! - Reranking for precision (GOD TIER 2026)
 
 mod hybrid;
+pub mod hyde;
 mod keyword;
 mod reranker;
 mod temporal;
@@ -29,3 +30,6 @@ pub use reranker::{
     Reranker, RerankerConfig, RerankerError, RerankedResult,
     DEFAULT_RERANK_COUNT, DEFAULT_RETRIEVAL_COUNT,
 };
+
+// v2.0: HyDE-inspired query expansion for improved semantic search
+pub use hyde::{classify_intent, expand_query, centroid_embedding, QueryIntent};