Add port mappings feature, update app icon, and enhance default instructions

- Add per-project port mapping configuration (host:container port pairs with
  TCP/UDP protocol) stored in project config and applied as Docker port
  bindings at container creation. Port changes trigger automatic container
  recreation via fingerprint detection.
- Create PortMappingsModal UI component following the same pattern as
  EnvVarsModal, integrated into ProjectCard config panel.
- Inject port mapping details into CLAUDE_INSTRUCTIONS so Claude inside the
  container knows which ports are available for testing services.
- Update default global instructions for new installs to encourage use of
  subagents for long-running and parallel tasks.
- Replace app icons with new v2 sun logo design for better visibility at
  small sizes (taskbar/dock).

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

app/src-tauri/src/models/app_settings.rs

@@ -7,7 +7,7 @@ fn default_true() -> bool {
 }
 
 fn default_global_instructions() -> Option<String> {
-    Some("If the project is not initialized with git, recommend to the user to initialize and use git to track changes. This makes it easier to revert should something break.".to_string())
+    Some("If the project is not initialized with git, recommend to the user to initialize and use git to track changes. This makes it easier to revert should something break.\n\nUse subagents frequently. For long-running tasks, break the work into parallel subagents where possible. When handling multiple separate tasks, delegate each to its own subagent so they can run concurrently.".to_string())
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]