Fix #266: Remove duplicate redirect causing JSON unmarshal error on n…

[Kaustubh1204]

Problem

Issue #266: kvctl commands fail with "unexpected end of JSON input" when connecting to non-loopback IP addresses via -H flag.

Root Cause

Duplicate c.Redirect() calls in RedirectIfNotLeader middleware (lines 78-79):

• Line 78: Correctly redirects using extracted peer address ✓
• Line 79: Immediately overwrites with raw session ID ✗

This creates an invalid redirect URL causing empty/malformed responses.

Solution

Remove the duplicate second redirect call (line 79).

Changes

• 1 line removed from server/middleware/middleware.go
• Minimal, focused fix with no other code changes

Fixes #266