refactor: fold single-consumer helper types into their owners

Consolidate small single-purpose types into the files that own them:
StreamResult into StreamAnalyzer, the Planning context records into
PlanningSessionContext, PrimeClock/PrimeSchedulerOptions into PrimeScheduler,
AgentMcpTools into LifecycleMcpTools, the locator subclasses into
InstallArtifactLocator, LogLineViewModel into DetailsIslandViewModel,
RepoImportItemViewModel into its modal, and StepViewModel into InstallPageViewModel.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/ClaudeDo.Worker/Planning/InteractiveLaunchContext.cs

@@ -1,6 +0,0 @@
-namespace ClaudeDo.Worker.Planning;
-
-public sealed record InteractiveLaunchContext(
-    string TaskId,
-    string WorkingDir,
-    string InitialPrompt);

src/ClaudeDo.Worker/Planning/PlanningMcpContext.cs

@@ -1,6 +0,0 @@
-namespace ClaudeDo.Worker.Planning;
-
-public sealed class PlanningMcpContext
-{
-    public required string ParentTaskId { get; init; }
-}

src/ClaudeDo.Worker/Planning/PlanningSessionContext.cs

@@ -1,5 +1,20 @@
 namespace ClaudeDo.Worker.Planning;
 
+public sealed record PlanningSessionFiles(
+    string SessionDirectory,
+    string SystemPromptPath,
+    string InitialPromptPath);
+
+public sealed record InteractiveLaunchContext(
+    string TaskId,
+    string WorkingDir,
+    string InitialPrompt);
+
+public sealed class PlanningMcpContext
+{
+    public required string ParentTaskId { get; init; }
+}
+
 public sealed record PlanningSessionStartContext(
     string ParentTaskId,
     string WorkingDir,

src/ClaudeDo.Worker/Planning/PlanningSessionFiles.cs

@@ -1,6 +0,0 @@
-namespace ClaudeDo.Worker.Planning;
-
-public sealed record PlanningSessionFiles(
-    string SessionDirectory,
-    string SystemPromptPath,
-    string InitialPromptPath);