fix: drop Intel Mac CI target, fix feature-gate dependency chain

ort-sys v2.0.0-rc.11 has no prebuilt ONNX Runtime binaries for
x86_64-apple-darwin, and vestige-mcp requires embeddings to compile.

- Remove x86_64-apple-darwin from CI release matrix (discontinued 2020)
- Fix vestige-mcp Cargo.toml: add default-features=false to vestige-core dep
- Extract sanitize_fts5_query to always-available fts.rs module
- Gate embeddings-only imports in storage/sqlite.rs behind #[cfg]

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

crates/vestige-core/src/lib.rs

@@ -82,6 +82,7 @@
 
 pub mod consolidation;
 pub mod fsrs;
+pub mod fts;
 pub mod memory;
 pub mod storage;