chore: pin opencadcodec 4f7bd51 (merlinnot codec fixes #56-#61)

Brings in: unchanged ACSH extrusion history and DIMASSOC records kept
byte for byte; native dynamic-action field layouts corrected; evaluation
graph expressions written as owned; evaluated block metadata copy;
source class numbers kept on same-version legacy saves; explicit block
attribute flags kept.

The dynamic-action model now names its fields after their native
meaning, so the object summaries read parameter ids, the move offsets'
distance multiplier and the lookup table's columns. The empty
PropertiesTable variant is gone; such tables stay opaque objects.

Pins opencadcodec 4f7bd51, opencadkernel 8186605, opencadgraph 048c9c5.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

plugins/opencad-python/Cargo.lock

@@ -1265,7 +1265,7 @@ dependencies = [
 [[package]]
 name = "opencadcodec"
 version = "0.5.5"
-source = "git+https://github.com/HakanSeven12/opencadcodec.git?rev=1109d52#1109d52f65ae8f00d75f43445908bff48807c0c5"
+source = "git+https://github.com/HakanSeven12/opencadcodec.git?rev=4f7bd51#4f7bd514a95329d8b0188ff7e3e04a820f529e23"
 dependencies = [
  "ahash 0.8.12",
  "anyhow",