refactor: drop the remaining single-implementation interfaces

IBaseDirtyChecker, IInteractiveLaunchSpecService and the LaunchSpec wrapper
had one implementation and one caller each; ProcessRunnerAdapter existed only
to give a static class an interface, and InstallArtifactLocator used
inheritance for two constructor arguments. The external MCP container now
shares its singletons through a Share<T> helper instead of 17 near-identical
registrations.

src/ClaudeDo.Worker/Planning/Interfaces/ITerminalLauncher.cs

@@ -2,7 +2,7 @@ namespace ClaudeDo.Worker.Planning;
 
 // Launches the Claude CLI in a visible terminal for human-driven planning sessions.
 // Not used for headless task execution (that path is ClaudeProcess, prompt over stdin)
-// nor for embedded ConPTY interactive sessions (those use IInteractiveLaunchSpecService).
+// nor for embedded ConPTY interactive sessions (those use InteractiveLaunchSpecService).
 public interface ITerminalLauncher
 {
     Task LaunchPlanningStartAsync(PlanningSessionStartContext ctx, CancellationToken cancellationToken);

src/ClaudeDo.Worker/Planning/WindowsTerminalLauncher.cs

@@ -27,7 +27,7 @@ namespace ClaudeDo.Worker.Planning;
 // Spawns the Claude CLI inside a visible Windows Terminal window for an interactive
 // planning session (start/resume). Headless task execution does NOT come through here —
 // that path is ClaudeProcess (prompt over stdin, no terminal) — nor does an embedded
-// ConPTY interactive session (IInteractiveLaunchSpecService), which reuses this class's
+// ConPTY interactive session (InteractiveLaunchSpecService), which reuses this class's
 // arg-building helpers (BuildResumeArgs, BuildPlanningStart/ResumeArgs) for a bare
 // Exe/Args pair instead of a wrapped pwsh command line.
 public sealed class WindowsTerminalLauncher : ITerminalLauncher
@@ -86,7 +86,7 @@ public sealed class WindowsTerminalLauncher : ITerminalLauncher
         return Task.CompletedTask;
     }
 
-    // The raw claude CLI args for a --resume launch, shared with IInteractiveLaunchSpecService
+    // The raw claude CLI args for a --resume launch, shared with InteractiveLaunchSpecService
     // (which needs the bare Exe/Args pair for a ConPTY host, not a wrapped pwsh command line).
     internal static IReadOnlyList<string> BuildResumeArgs(string claudeSessionId) =>
         new[] { "--resume", claudeSessionId };
@@ -99,7 +99,7 @@ public sealed class WindowsTerminalLauncher : ITerminalLauncher
         BuildPwshCommand(claudePath, BuildPlanningStartArgs(ctx));
 
     // The raw claude CLI args for an interactive planning START, shared with the embedded-ConPTY
-    // planning path (IInteractiveLaunchSpecService), which needs the bare Exe/Args pair rather than
+    // planning path (InteractiveLaunchSpecService), which needs the bare Exe/Args pair rather than
     // a pwsh-wrapped command line. Arg order matters: variadic flags (--allowedTools, --add-dir)
     // come first; the single-line kickoff prompt is positional, so it must follow a single-value
     // flag (--append-system-prompt-file) or a variadic flag would swallow it.
@@ -176,7 +176,7 @@ public sealed class WindowsTerminalLauncher : ITerminalLauncher
             ?? throw new TerminalLaunchException("Failed to start Windows Terminal process.");
     }
 
-    // Not private: reused by IInteractiveLaunchSpecService to resolve the claude executable
+    // Not private: reused by InteractiveLaunchSpecService to resolve the claude executable
     // for a ConPTY-hosted launch spec the same way a wt-launched terminal resolves it.
     internal static string? Resolve(string pathOrName)
     {