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>

compliance-core/src/models/issue.rs

@@ -42,7 +42,7 @@ impl std::fmt::Display for IssueStatus {
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct TrackerIssue {
     #[serde(rename = "_id", skip_serializing_if = "Option::is_none")]
-    pub id: Option<mongodb::bson::oid::ObjectId>,
+    pub id: Option<bson::oid::ObjectId>,
     pub finding_id: String,
     pub tracker_type: TrackerType,
     pub external_id: String,