fix(daemon): make Duration import unconditional for Windows build

Follow-up to f8a191d (#50 fix). The `check_reachability(timeout: Duration)`
method signature uses `Duration` unconditionally, but `use std::time::Duration`
was gated behind `#[cfg(unix)]`. macOS/Linux builds (where I ran cargo
check) had the import in scope via the unix-only body, but the Windows
target — where the non-unix arm renders `let _ = timeout` and never
touches `Duration` — failed compile because the signature still
references the type.

Drop the cfg gate on the Duration import. Unix and Windows now share
the same import line. (`UnixStream`, `Read`, `Write`, and the
`coven_home` helper stay gated — they're only used inside the unix
arms.)

The v0.0.17 Release workflow's Windows build was the only one that
failed on this; macOS/Linux builds were green. Re-dispatching now.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: BunsDev

src-rust/crates/core/src/coven_daemon.rs

@@ -11,7 +11,9 @@ use std::io::{Read, Write};
 use std::os::unix::net::UnixStream;
 #[cfg(unix)]
 use std::path::PathBuf;
-#[cfg(unix)]
+// `Duration` appears in the public `check_reachability(timeout)` signature,
+// so its import can't be gated on `cfg(unix)` even though the only real
+// implementation lives there.
 use std::time::Duration;
 
 use serde::{Deserialize, Serialize};