fix(felhomsshd): persist claimed port in agent StateDir (non-root can't write /etc)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PSK5g6qYLknKj8u3QAFEr6

internal/felhomsshd/claim.go

@@ -1,11 +1,6 @@
 package felhomsshd
 
-import (
-	"fmt"
-	"os"
-	"strconv"
-	"strings"
-)
+import "fmt"
 
 // Candidates is the ordered OOB-port candidate list (spike §2). First free wins; NEVER :22 or a
 // random port. Package-var (not const) so tests can shrink it.
@@ -42,24 +37,3 @@ func claimPort(candidates []int, isFree portProbe, readPersisted func() (int, bo
 	}
 	return 0, ErrPortsExhausted
 }
-
-// readPortFile parses PortFile → (port, ok). A missing/garbage file → (0,false).
-func readPortFile() (int, bool) {
-	raw, err := os.ReadFile(PortFile)
-	if err != nil {
-		return 0, false
-	}
-	p, err := strconv.Atoi(strings.TrimSpace(string(raw)))
-	if err != nil || p < 1 || p > 65535 {
-		return 0, false
-	}
-	return p, true
-}
-
-// writePortFile persists the claimed port (0644 — a port is not a secret).
-func writePortFile(port int) error {
-	if err := os.MkdirAll(ConfDir, 0o755); err != nil {
-		return err
-	}
-	return os.WriteFile(PortFile, []byte(strconv.Itoa(port)+"\n"), 0o644)
-}