Add SFV panel: compute/verify CRC32/MD5/SHA1 checksums, .sfv/.md5/.sha1 sidecar files

Fully local feature - no network access, no credentials. New aurora-curator-core::sfv
module streams file hashing in 64KB chunks and handles both the traditional .sfv
format (CRC32, "name checksum" layout) and the GNU coreutils md5sum/sha1sum sidecar
convention (.md5/.sha1, "checksum  name" layout), dispatched on a shared ChecksumKind
enum. New src-tauri/src/sfv.rs wraps it in three Tauri commands - compute_checksums
(per-file error isolation), save_checksum_file (native Save dialog), and
verify_checksum_file (resolves each entry against the checksum file's own parent
directory, reports OK/Mismatch/Missing per entry). New SfvPanel.tsx/.css wires it all
into the sidebar's SFV screen - load files, pick a checksum type, Compute, Save, or
Verify against an existing checksum file.

14 new core-crate tests + 1 new src-tauri test, all passing (workspace: 160/160).
Verified end-to-end with a 22-check Playwright script against npm run dev.

Cargo.lock

@@ -119,12 +119,15 @@ dependencies = [
 name = "aurora-curator-core"
 version = "0.1.0"
 dependencies = [
+ "crc32fast",
+ "md-5",
  "mockito",
  "regex",
  "reqwest 0.12.28",
  "rhai",
  "serde",
  "serde_json",
+ "sha1",
  "thiserror 1.0.69",
  "tokio",
 ]
@@ -1933,6 +1936,16 @@ dependencies = [
  "web_atoms",
 ]
 
+[[package]]
+name = "md-5"
+version = "0.10.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d89e7ee0cfbedfc4da3340218492196241d89eefb6dab27de5df917a6d2e78cf"
+dependencies = [
+ "cfg-if",
+ "digest",
+]
+
 [[package]]
 name = "memchr"
 version = "2.8.3"
@@ -3266,6 +3279,17 @@ dependencies = [
  "stable_deref_trait",
 ]
 
+[[package]]
+name = "sha1"
+version = "0.10.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a978451301f4db1d02937a4ab3ccce137717b81826e79b7d49ffe3244a13c3b8"
+dependencies = [
+ "cfg-if",
+ "cpufeatures 0.2.17",
+ "digest",
+]
+
 [[package]]
 name = "sha2"
 version = "0.10.9"