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.toml

@@ -7,7 +7,7 @@ unwrap_used = "deny"
 expect_used = "deny"
 
 [workspace.dependencies]
-compliance-core = { path = "compliance-core" }
+compliance-core = { path = "compliance-core", default-features = false }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 tokio = { version = "1", features = ["full"] }