✨ Diagnostic Manager

先定位編輯器的 Issue Navigator 和 Line Annotations 元件，接著追蹤它們目前如何接收診斷資料。根據需求定義 DiagnosticManager 和 DiagnosticIssue，並依檔案及可觀察的變更分組更新；完成的條件是兩個元件都能使用 manager 作為共用的診斷來源。

Description

Introduce a DiagnosticManager responsible for managing and publishing diagnostics (e.g., build errors, linter warnings, language server issues) grouped by file. This manager will serve as the single source of truth for diagnostics across the editor, and its contents will drive visual components such as the Issue Navigator and Line Annotations.

Requirements

• Create a DiagnosticManager class conforming to ObservableObject
• Store diagnostics as a flat list or grouped by file:

  @Published var issues: [DiagnosticIssue]
  

• Define a DiagnosticIssue model:

  struct DiagnosticIssue: Identifiable, Hashable {
      let id: UUID = UUID()
      let file: URL
      let line: Int
      let column: Int?
      let message: String
      let severity: Severity
      let source: String?
      let fixItSuggestion: String?
  
      enum Severity {
          case error, warning, info, live
      }
  }
  

• Add convenience accessors:

  var issuesByFile: [URL: [DiagnosticIssue]]
  func issues(for file: URL) -> [DiagnosticIssue]
  

• Add a way to update issues by file, e.g.:

  func setIssues(_ issues: [DiagnosticIssue], for file: URL)
  func clearIssues(for file: URL)
  

Additional Context

This manager will be used by multiple parts of the app, including the Issue Navigator and Line Annotations. It should be reactive and efficient, allowing UI components to automatically update when diagnostics change.

Future extensions may include filtering, debouncing updates, or supporting different diagnostics sources (build system, LSP, etc.).

Related Issues

• #354
• #2015
• https://github.com/CodeEditApp/CodeEditSourceEditor/issues/297