Fix dashboard wasm build and feature-gate mongodb for wasm compatibility

- Feature-gate mongodb in compliance-core (optional, default on) so wasm
  builds don't pull in tokio/mio via mongodb
- Use bson v2 directly for ObjectId types (wasm-compatible)
- Restructure dashboard infrastructure/mod.rs: server function modules
  always compiled (for RPC stubs), server-only modules cfg-gated
- Remove reqwest from dashboard web feature (not needed, data flows
  through server functions)
- Add .gitignore

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

Cargo.lock

@@ -436,6 +436,7 @@ dependencies = [
 name = "compliance-core"
 version = "0.1.0"
 dependencies = [
+ "bson",
  "chrono",
  "hex",
  "mongodb",