feat: recipe durability guard — prevents build system from deleting local recipes

Add guard-recipes.sh with four modes:
- --verify: check all local/recipes have correct symlinks into recipes/
- --fix: repair broken symlinks (run before builds)
- --save-all: snapshot all recipe.toml into local/recipes/
- --restore: recreate all symlinks from local/recipes/ (run after sync-upstream)

Wired into apply-patches.sh (post-patch) and sync-upstream.sh (post-sync).
This prevents the build system from deleting recipe files during
cargo cook, make distclean, or upstream source refresh.

local/recipes/system/hwrngd/source/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "hwrngd"
+version = "0.1.0"
+edition = "2024"
+
+[[bin]]
+name = "hwrngd"
+path = "src/main.rs"
+
+[dependencies]
+libredox = { version = "0.1", features = ["call", "std"] }
+log = { version = "0.4", features = ["std"] }
+redox-scheme = "0.11"
+syscall = { package = "redox_syscall", version = "0.7", features = ["std"] }