refactor: replace task-specific panel store with centralized layout store

- Create centralized panelLayoutStore managing layouts for multiple tasks
- Add comprehensive unit tests
- Extract panel manipulation logic into helpers
- Add constants for default panel IDs and sizes
- Enhance panelTree utilities for tree manipulation

Author: jonathanlab

src/renderer/features/panels/constants/panelConstants.ts

@@ -0,0 +1,27 @@
+export const PANEL_SIZES = {
+  MIN_PANEL_SIZE: 15,
+  DEFAULT_SPLIT: [70, 30] as const,
+  EVEN_SPLIT: [50, 50] as const,
+  SIZE_DIFF_THRESHOLD: 0.1,
+} as const;
+
+export const UI_SIZES = {
+  TAB_HEIGHT: 40,
+  TAB_LABEL_MAX_WIDTH: 200,
+  DROP_ZONE_SIZE: "20%",
+} as const;
+
+export const DEFAULT_PANEL_IDS = {
+  ROOT: "root",
+  MAIN_PANEL: "main-panel",
+  RIGHT_GROUP: "right-group",
+  DETAILS_PANEL: "details-panel",
+  FILES_PANEL: "files-panel",
+} as const;
+
+export const DEFAULT_TAB_IDS = {
+  LOGS: "logs",
+  SHELL: "shell",
+  DETAILS: "details",
+  FILES: "files",
+} as const;