feat: add OpenTelemetry trace spans to all handlers and pipeline functions

Add #[tracing::instrument(skip_all)] to 44 functions:
- 19 API handlers in mod.rs
- 3 chat handlers, 6 DAST handlers, 7 graph handlers
- 2 pipeline orchestrator functions
- 7 scanner functions (sbom, semgrep, gitleaks, cve, lint, patterns)

This generates trace spans for SigNoz visibility into request
latency, scan pipeline stages, and error tracking.

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

compliance-agent/src/api/handlers/dast.rs

@@ -42,6 +42,7 @@ fn default_rate_limit() -> u32 {
 }
 
 /// GET /api/v1/dast/targets — List DAST targets
+#[tracing::instrument(skip_all)]
 pub async fn list_targets(
     Extension(agent): AgentExt,
     Query(params): Query<PaginationParams>,
@@ -73,6 +74,7 @@ pub async fn list_targets(
 }
 
 /// POST /api/v1/dast/targets — Add a new DAST target
+#[tracing::instrument(skip_all)]
 pub async fn add_target(
     Extension(agent): AgentExt,
     Json(req): Json<AddTargetRequest>,
@@ -99,6 +101,7 @@ pub async fn add_target(
 }
 
 /// POST /api/v1/dast/targets/:id/scan — Trigger DAST scan
+#[tracing::instrument(skip_all)]
 pub async fn trigger_scan(
     Extension(agent): AgentExt,
     Path(id): Path<String>,
@@ -138,6 +141,7 @@ pub async fn trigger_scan(
 }
 
 /// GET /api/v1/dast/scan-runs — List DAST scan runs
+#[tracing::instrument(skip_all)]
 pub async fn list_scan_runs(
     Extension(agent): AgentExt,
     Query(params): Query<PaginationParams>,
@@ -170,6 +174,7 @@ pub async fn list_scan_runs(
 }
 
 /// GET /api/v1/dast/findings — List DAST findings
+#[tracing::instrument(skip_all)]
 pub async fn list_findings(
     Extension(agent): AgentExt,
     Query(params): Query<PaginationParams>,
@@ -202,6 +207,7 @@ pub async fn list_findings(
 }
 
 /// GET /api/v1/dast/findings/:id — Finding detail with evidence
+#[tracing::instrument(skip_all)]
 pub async fn get_finding(
     Extension(agent): AgentExt,
     Path(id): Path<String>,