Add audit plan for slugify branch pass 3 and implement critical fixes

- Introduced a comprehensive audit plan for the slugify branch, detailing findings from a holistic review of 110 files, including 1 critical bug and 2 correctness issues.
- Completed todos addressing model JSON renaming, syncback updates, and test enhancements for roundtrip fidelity.
- Added tests for reserved names and ensured correct handling of slugified instances, preserving compound extensions in model files.
- Refactored change processing logic to correctly manage the `name` field in model files, enhancing metadata handling and ensuring compliance with round-trip identity standards.

rojo-test/build-tests/reserved_name_override/default.project.json5

@@ -0,0 +1,10 @@
+{
+  "name": "reserved_name_override",
+  "tree": {
+    "$className": "DataModel",
+    "ReplicatedStorage": {
+      "$className": "ReplicatedStorage",
+      "$path": "src"
+    }
+  }
+}

rojo-test/build-tests/reserved_name_override/src/CON_.luau

@@ -0,0 +1 @@
+return "I am CON"

rojo-test/build-tests/reserved_name_override/src/CON_.meta.json5

@@ -0,0 +1,3 @@
+{
+  "name": "CON"
+}

rojo-test/build-tests/reserved_name_override/src/PRN_.luau

@@ -0,0 +1 @@
+return "I am PRN"

rojo-test/build-tests/reserved_name_override/src/PRN_.meta.json5

@@ -0,0 +1,3 @@
+{
+  "name": "PRN"
+}