refactor(config): consolidate model aliases into ModelRegistry

Replaces three scattered model lists (ListSettingsModalViewModel,
DetailsIslandViewModel, GeneralSettingsTabViewModel) and the hardcoded
planning model with a single source. Planning launcher now uses the
opus alias instead of pinning claude-opus-4-7.

src/ClaudeDo.Worker/Hub/WorkerHub.cs

@@ -210,7 +210,7 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
         {
             Id = AppSettingsEntity.SingletonId,
             DefaultClaudeInstructions = dto.DefaultClaudeInstructions ?? "",
-            DefaultModel = dto.DefaultModel ?? "sonnet",
+            DefaultModel = dto.DefaultModel ?? ModelRegistry.DefaultAlias,
             DefaultMaxTurns = dto.DefaultMaxTurns,
             DefaultPermissionMode = dto.DefaultPermissionMode ?? "bypassPermissions",
             WorktreeStrategy = dto.WorktreeStrategy ?? "sibling",

src/ClaudeDo.Worker/Planning/WindowsTerminalPlanningLauncher.cs

@@ -7,13 +7,14 @@
 // No cmd /k shim — arbitrary initial-prompt content would be re-parsed by cmd.exe otherwise.
 
 using System.Diagnostics;
+using ClaudeDo.Data.Models;
 
 namespace ClaudeDo.Worker.Planning;
 
 public sealed class WindowsTerminalPlanningLauncher : IPlanningTerminalLauncher
 {
     private const string AllowedTools = "mcp__claudedo__*,Read,Grep,Glob,WebFetch,WebSearch,Skill";
-    private const string Model = "claude-opus-4-7";
+    private const string Model = ModelRegistry.PlanningAlias;
 
     private readonly string _wtPath;
     private readonly string _claudePath;