v0.20.1: board-wide same-net-pad-clearance (#581), graphics-never-stubs (#583), green test suite

Python-only release -- the Rust crate stays 0.20.0 and the runtime
resolver keeps using the published 0.20.0 binaries (CI re-attaches them).

Headline changes since v0.20.0:
- #581: --same-net-pad-clearance > 0 is a board-wide via-in-pad
  prohibition honored by EVERY via placement (escape vias, the #189
  via-in-pad rescue, swap pad vias, plane taps/joins, rescue routes, the
  sub-grid via nudge; BGA under-pad escapes run dog-bone, QFN refuses
  via-in-pad). The value persists in the .kicad_pro so a whole chain
  inherits it; the flag exists on planes/route/route_diff/repair/
  bga_fanout/qfn_fanout; the GUI controls moved to the Basic tab as a
  session-wide policy. -1 AND 0 preserve the previous behavior exactly.
- #583: net-tagged copper GRAPHICS are never walked as stubs or
  relayered -- fixes emitted copper violating clearance against board
  copper graphics (KiCad-confirmed on apple1_aci_card).
- #582 + live-board zone-deletion authority + planes-GUI ZONES report.
- Stress harness: relaunches archive (never clobber) manifests; steps
  cannot outlive their shell.
- run_all is green for the first time (250/0): 4 chronic failures were
  #522 subprocess path debris (vacuous passes), 1 a stale expectation.

check_release_version.py --tag v0.20.1: OK. Parity audit at 4b0479a:
no gaps, all four gates green, copper sets identical.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0176bS9zFYRSx67KWmRpVPuD

Author: drandyhaas

VERSION

@@ -1 +1 @@
-0.20.0
+0.20.1

metadata.json

@@ -25,7 +25,7 @@
   ],
   "versions": [
     {
-      "version": "0.20.0",
+      "version": "0.20.1",
       "status": "testing",
       "kicad_version": "9.0",
       "runtime": "swig",
@@ -34,7 +34,7 @@
         "macos",
         "windows"
       ],
-      "download_url": "https://github.com/drandyhaas/KiCadRoutingTools/releases/download/v0.20.0/KiCadRoutingTools-0.20.0.zip",
+      "download_url": "https://github.com/drandyhaas/KiCadRoutingTools/releases/download/v0.20.1/KiCadRoutingTools-0.20.1.zip",
       "download_sha256": "0000000000000000000000000000000000000000000000000000000000000000",
       "download_size": 0,
       "install_size": 0