Implement Week 5 CDC & Delta Detection with Oracle fixes

- Add CdcChunker using FastCDC v3 (16KB/64KB/256KB chunks)
- Add DeltaDetector with scan_origin() returning ScannedFile (no FileId assignment)
- Add OriginWatcher with inotify and 200ms debounce using tokio::spawn
- Fix LocalOrigin::read() to loop until all bytes read
- Add read_full() method to Origin trait
- Add mtime field to ChunkManifest
- Update ContentFetcher to use CDC chunking
- Update bandwidth reduction test to assert >90% (NFR-6.4)

Tests: 71 pass (+11 new)

musicfs/crates/musicfs-sync/Cargo.toml

@@ -4,3 +4,19 @@ version.workspace = true
 edition.workspace = true
 
 [dependencies]
+musicfs-core = { path = "../musicfs-core" }
+musicfs-origins = { path = "../musicfs-origins" }
+
+fastcdc = "3"
+xxhash-rust = { version = "0.8", features = ["xxh64"] }
+notify = "6"
+rmp-serde = "1"
+
+tokio = { workspace = true }
+tracing = { workspace = true }
+thiserror = { workspace = true }
+serde = { workspace = true }
+async-trait = { workspace = true }
+
+[dev-dependencies]
+tempfile = { workspace = true }