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/Cargo.toml

@@ -0,0 +1,25 @@
+[workspace]
+members = [
+    "fat-blockdev",
+    "fatd",
+    "fat-mkfs",
+    "fat-label",
+    "fat-check",
+]
+resolver = "3"
+
+[workspace.package]
+version = "0.1.0"
+edition = "2024"
+license = "MIT"
+
+[workspace.dependencies]
+fatfs = "0.3.6"
+fscommon = "0.1.1"
+redox_syscall = "0.7.3"
+redox-scheme = "0.11.0"
+libredox = "0.1.13"
+redox-path = "0.3.0"
+log = "0.4"
+env_logger = "0.11"
+libc = "0.2"