Add FAT12/16/32 scheme daemon, management tools, and build integration

5-crate Rust workspace implementing full VFAT support: fatd scheme daemon
(FSScheme with open/read/write/mkdir/unlink/rename/fstat), fat-mkfs (create
FAT12/16/32 with labels and cluster size), fat-label (read/write BPB + root-dir
volume labels), fat-check (verify + repair dirty flags, FSInfo, lost clusters,
orphaned LFN). 60 unit tests, 0 unwrap in production code. Included in all 5
redbear configs via redbear-device-services.toml.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

local/recipes/core/fatd/source/fat-check/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "fat-check"
+description = "FAT filesystem checker (fsck.fat equivalent)"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[[bin]]
+name = "fat-check"
+path = "src/main.rs"
+
+[dependencies]
+fat-blockdev = { path = "../fat-blockdev" }
+fatfs.workspace = true
+fscommon.workspace = true
+log.workspace = true