Merge m5max128gitea Web GUI + Backup features with local SMB fixes

Merged from m5max128gitea:
- Web GUI Phase 11: User/Share/Dashboard management
- NFS stub + nfsserve dependency
- Backup/Snapshot REST API endpoints
- Integration tests for user/share management
- Feature comparison docs (Proxmox/Unraid/OpenNAS)

Preserved from local:
- upload_path config (tested stable)
- delete_file/preview_file routes (MyFiles)
- SSH async I/O
- auth.sqlite (important user data)
- Admin WebDAV + CorsLayer

Conflicts resolved:
- AGENTS.md: kept remote (more complete docs)
- myfiles.rs: kept local upload_path
- server.rs: merged both routes (preview + backup)
- auth.sqlite: preserved local (important user data)

Cargo.lock

@@ -720,6 +720,18 @@ dependencies = [
  "shlex",
 ]
 
+[[package]]
+name = "ccm"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ae3c82e4355234767756212c570e29833699ab63e6ffd161887314cc5b43847"
+dependencies = [
+ "aead 0.5.2",
+ "cipher 0.4.4",
+ "ctr 0.9.2",
+ "subtle",
+]
+
 [[package]]
 name = "ccm"
 version = "0.6.0-rc.3"
@@ -2961,6 +2973,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "lz4_flex"
+version = "0.11.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "373f5eceeeab7925e0c1098212f2fbc4d416adec9d35051a6ab251e824c1854a"
+dependencies = [
+ "twox-hash",
+]
+
 [[package]]
 name = "lz4_flex"
 version = "0.13.1"
@@ -3025,7 +3046,9 @@ dependencies = [
  "lazy_static",
  "ldap3",
  "log",
+ "lz4_flex 0.11.6",
  "md5 0.8.0",
+ "nfsserve",
  "nix 0.29.0",
  "once_cell",
  "poly1305 0.8.0",
@@ -5468,12 +5491,13 @@ name = "smb-server"
 version = "0.4.1"
 dependencies = [
  "aes 0.8.4",
+ "aes-gcm 0.10.3",
  "async-trait",
  "binrw",
  "bytes",
  "cap-std",
+ "ccm 0.5.0",
  "cmac 0.7.2",
- "ctr 0.9.2",
  "getrandom 0.4.2",
  "hex",
  "hmac 0.12.1",
@@ -5497,7 +5521,7 @@ dependencies = [
  "aes 0.9.1",
  "aes-gcm 0.11.0-rc.4",
  "async-trait",
- "ccm",
+ "ccm 0.6.0-rc.3",
  "cmac 0.8.0-rc.5",
  "digest 0.11.3",
  "env_logger",
@@ -5505,7 +5529,7 @@ dependencies = [
  "getrandom 0.4.2",
  "hmac 0.13.0",
  "log",
- "lz4_flex",
+ "lz4_flex 0.13.1",
  "md-5 0.11.0",
  "md4 0.11.0",
  "num_enum",