v0.16.1: route_diff --layer-costs, diff-pair detection + GUI-parity fixes

- route_diff --layer-costs: per-layer bias for coupled diff pairs (#193;
  Rust crate -> 0.16.2)
- diff-pair detection: don't misread a _t_/_c_ infix as DDR true/complement (#192)
- GUI parity: impedance diff control, plane-repair max-search-radius,
  rule-area keepouts; claude_plan carries layer_costs/impedance on route_diff
- stress harness: A/B coupled-diff + timing/RSS metrics, queue watchdog

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: drandyhaas

VERSION

@@ -1 +1 @@
-0.16.0
+0.16.1

metadata.json

@@ -25,7 +25,7 @@
   ],
   "versions": [
     {
-      "version": "0.16.0",
+      "version": "0.16.1",
       "status": "testing",
       "kicad_version": "9.0",
       "runtime": "swig",
@@ -34,7 +34,7 @@
         "macos",
         "windows"
       ],
-      "download_url": "https://github.com/drandyhaas/KiCadRoutingTools/releases/download/v0.16.0/KiCadRoutingTools-0.16.0.zip",
+      "download_url": "https://github.com/drandyhaas/KiCadRoutingTools/releases/download/v0.16.1/KiCadRoutingTools-0.16.1.zip",
       "download_sha256": "0000000000000000000000000000000000000000000000000000000000000000",
       "download_size": 0,
       "install_size": 0