Add magic bytes deployment system for agent modes

- Agent config: Added EmbeddedConfig struct and RunMode enum for
  filename-based mode detection (Viewer, TempSupport, PermanentAgent)
- Agent main: Updated to detect run mode from filename or embedded config
- Server: Added /api/download/* endpoints for generating configured binaries
  - /api/download/viewer - Downloads GuruConnect-Viewer.exe
  - /api/download/support?code=123456 - Downloads GuruConnect-123456.exe
  - /api/download/agent?company=X&site=Y - Downloads with embedded config
- Dashboard: Updated Build tab with Quick Downloads and Permanent Agent Builder
- Included base agent binary in static/downloads

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

server/src/main.rs

@@ -233,6 +233,11 @@ async fn main() -> Result<()> {
         .route("/api/releases/:version", put(api::releases::update_release))
         .route("/api/releases/:version", delete(api::releases::delete_release))
 
+        // Agent downloads (no auth - public download links)
+        .route("/api/download/viewer", get(api::downloads::download_viewer))
+        .route("/api/download/support", get(api::downloads::download_support))
+        .route("/api/download/agent", get(api::downloads::download_agent))
+
         // HTML page routes (clean URLs)
         .route("/login", get(serve_login))
         .route("/dashboard", get(serve_dashboard))