audit fixes, repo restructure, and documentation

Soundness and performance audit (17 fixes):
- See AUDIT.md for full details and @claude comments in code

Repo restructure:
- Inline json-ptr and json-patch submodules as regular directories
- Remove cbor submodule, replace serde_cbor with ciborium
- Rename patch-db/ -> core/, patch-db-macro/ -> macro/,
  patch-db-macro-internals/ -> macro-internals/, patch-db-util/ -> util/
- Purge upstream CI/CD, bench, and release cruft from json-patch
- Remove .gitmodules

Test fixes:
- Fix proptest doesnt_crash (unique file paths, proper close/cleanup)
- Add PatchDb::close() for clean teardown

Documentation:
- Add README.md, ARCHITECTURE.md, CONTRIBUTING.md, CLAUDE.md, AUDIT.md
- Add TSDocs to TypeScript client exports

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

json-patch/specs/merge_tests.json

@@ -0,0 +1,92 @@
+[
+  {
+    "comment": "1. introduction",
+    "doc": {
+      "a": "b",
+      "c": {
+        "d": "e",
+        "f": "g"
+      }
+    },
+    "patch": {
+      "a": "z",
+      "c": {
+        "f": null
+      }
+    },
+    "expected": {
+      "a": "z",
+      "c": {
+        "d": "e"
+      }
+    },
+    "merge": true
+  },
+  {
+    "comment": "3. example",
+    "doc": {
+      "title": "Goodbye!",
+      "author": {
+        "givenName": "John",
+        "familyName": "Doe"
+      },
+      "tags": [
+        "example",
+        "sample"
+      ],
+      "content": "This will be unchanged"
+    },
+    "patch": {
+      "title": "Hello!",
+      "phoneNumber": "+01-123-456-7890",
+      "author": {
+        "familyName": null
+      },
+      "tags": [
+        "example"
+      ]
+    },
+    "expected": {
+      "title": "Hello!",
+      "author": {
+        "givenName": "John"
+      },
+      "tags": [
+        "example"
+      ],
+      "content": "This will be unchanged",
+      "phoneNumber": "+01-123-456-7890"
+    },
+    "merge": true
+  },
+  {
+    "comment": "replacing non-object",
+    "doc": {
+      "title": "Goodbye!",
+      "author": {
+        "givenName": "John"
+      },
+      "tags": [
+        "example",
+        "sample"
+      ],
+      "content": "This will be unchanged"
+    },
+    "patch": {
+      "tags": {
+        "kind": "example"
+      }
+    },
+    "expected": {
+      "title": "Goodbye!",
+      "author": {
+        "givenName": "John"
+      },
+      "tags": {
+        "kind": "example"
+      },
+      "content": "This will be unchanged"
+    },
+    "merge": true
+  }
+]