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>

README.md

@@ -0,0 +1,81 @@
+# patch-db
+
+A database that tracks state updates as [RFC 6902 JSON Patches](https://tools.ietf.org/html/rfc6902). Enables observable, event-driven state management with a Rust backend and TypeScript client.
+
+## Overview
+
+patch-db stores your application state as a single JSON document. Instead of opaque writes, every mutation is recorded as a JSON Patch — a sequence of add/remove/replace operations. Subscribers receive only the patches relevant to the subtree they're watching, making it efficient for UIs that need to react to fine-grained state changes.
+
+### Key properties
+
+- **Event-sourced** — patches are the source of truth, not snapshots
+- **Observable** — subscribers watch arbitrary subtrees via JSON Pointers and receive scoped patches in real time
+- **Persistent** — the Rust backend writes to disk with CBOR serialization, automatic compaction, and crash-safe backup files
+- **Type-safe** — derive macros on the Rust side; generic type parameters and deep `watch$()` overloads on the TypeScript side
+- **Immutable values** — the Rust side uses `imbl_value::Value` for efficient structural sharing
+
+## Quick start
+
+### Rust
+
+Add to your `Cargo.toml`:
+
+```toml
+[dependencies]
+patch-db = { git = "https://github.com/Start9Labs/patch-db" }
+```
+
+```rust
+use patch_db::PatchDb;
+use json_ptr::ROOT;
+
+#[tokio::main]
+async fn main() -> Result<(), patch_db::Error> {
+    let db = PatchDb::open("my.db").await?;
+
+    // Write a value
+    db.put(&ROOT, &serde_json::json!({ "count": 0 })).await?;
+
+    // Read it back
+    let dump = db.dump(&ROOT).await;
+    println!("revision {}: {}", dump.id, dump.value);
+
+    // Subscribe to changes
+    let mut watch = db.watch(ROOT.to_owned()).await;
+    // watch implements Stream — use it with tokio, futures, etc.
+
+    Ok(())
+}
+```
+
+### TypeScript
+
+```typescript
+import { PatchDB, Dump, Update } from 'patch-db'
+import { Observable } from 'rxjs'
+
+interface AppState {
+  users: { [id: string]: { name: string; online: boolean } }
+  settings: { theme: string }
+}
+
+// source$ delivers updates from the server (WebSocket, SSE, etc.)
+const source$: Observable<Update<AppState>[]> = getUpdatesFromServer()
+
+const db = new PatchDB<AppState>(source$)
+db.start()
+
+// Watch a deeply nested path — fully type-safe
+db.watch$('settings', 'theme').subscribe(theme => {
+  console.log('Theme changed:', theme)
+})
+```
+
+## Further reading
+
+- [ARCHITECTURE.md](ARCHITECTURE.md) — project structure, crate/package details, data flow, storage format
+- [CONTRIBUTING.md](CONTRIBUTING.md) — environment setup, build commands, testing, code style
+
+## License
+
+MIT