ci fix: move [target.'cfg(unix)'.dependencies] after main [dependencies]

Placing a new table header before eframe silently scoped it into the
unix-only target table, so Windows builds lost the dependency entirely:

  error[E0432]: unresolved import `eframe`
  use of unresolved module or unlinked crate `eframe`

(Builds green on Mac/Linux because those hit cfg(unix) == true. Windows
was the only casualty.)

Moved the [target.'cfg(unix)'.dependencies] block to the end of
Cargo.toml, after the optional eframe line, so the main [dependencies]
table stays intact for all targets. Added a comment so this foot-gun
can't return.

Cargo.toml

@@ -46,12 +46,6 @@ flate2 = "1"
 directories = "5"
 futures-util = { version = "0.3", default-features = false, features = ["std"] }
 
-# libc is only referenced for the RLIMIT_NOFILE bump on Unix (issue #8 —
-# OpenWRT routers ship a very low fd limit that gets hit quickly under normal
-# traffic). Already pulled in transitively via tokio, so zero new weight.
-[target.'cfg(unix)'.dependencies]
-libc = "0.2"
-
 # Optional UI dep: only pulled in when --features ui is set.
 eframe = { version = "0.28", default-features = false, features = [
     "default_fonts",
@@ -59,6 +53,15 @@ eframe = { version = "0.28", default-features = false, features = [
     "persistence",
 ], optional = true }
 
+# Unix-only deps. Must come after `[dependencies]` because starting a new
+# table here otherwise ends the main one — anything below it (incl. eframe)
+# would end up scoped to cfg(unix) and disappear on Windows builds.
+# libc is referenced for the RLIMIT_NOFILE bump (issue #8 — OpenWRT routers
+# ship a very low fd limit that fills up fast under browser load). Already
+# pulled in transitively via tokio, so zero new weight.
+[target.'cfg(unix)'.dependencies]
+libc = "0.2"
+
 [profile.release]
 panic = "abort"
 codegen-units = 1