fix(recovery): resolve metadata MAC desync after recovery (R-NEW-1) & complete release workflow (CI-01)

- R-NEW-1: Recalculate metadata HMAC upon recovery-key restore and mark backup restores as PendingRebuild to rebuild transparently on first mount
- CI-01: Update release.yaml to compile both Windows x86_64 and Linux musl with pinned Zig 0.16.0 and cargo-zigbuild 0.23.4
- W-1: Implement statvfs quota determination on Unix via libc
- Add RELEASE_PROCESS.md documenting release architecture and steps
- Bump version to 0.9.2 across manifests, lockfile, docs, Scoop and WinGet

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "sanctum"
-version = "0.9.1"
+version = "0.9.2"
 edition = "2021"
 authors = ["Harald Pansi <harald@pansi.eu>", "Sanctum Engineering Team"]
 description = "Verschlüsselter Ein-Datei-Container unter Windows im reinen Userland via WebDAV"
@@ -48,6 +48,9 @@ tempfile = "3"
 [target.'cfg(windows)'.dependencies]
 tray-item = "0.10"
 
+[target.'cfg(unix)'.dependencies]
+libc = "0.2"
+
 [profile.release]
 opt-level = 3
 lto = true