fix(worker): harden CLI injection, stuck-Running, chain wedge, and Fail guard

1. ArgumentList (fix injection): ClaudeArgsBuilder.Build() now returns
   IReadOnlyList<string>; ClaudeProcess populates ProcessStartInfo.ArgumentList
   instead of Arguments, so values like system prompts are never shell-split.
   DailyPrepPrompt, RefinePrompt, and WeekReportService migrated similarly.
   All IClaudeProcess fakes updated.

2. ContinueAsync exception guard: wrap RunOnceAsync in try/catch matching
   the RunAsync pattern so an unexpected exception never leaves the task
   stuck in Running status.

3. Planning chain cascade: OnChildFinishedAsync now calls CancelAsync on
   the immediate blocked successor when a child fails or is cancelled,
   triggering a recursive cascade that clears the entire remaining chain
   instead of leaving it wedged.

4. FailAsync guard: restrict valid source states to Running and Queued;
   WaitingForReview -> Failed is now rejected, preventing an invalid
   transition that could corrupt the review workflow.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ClaudeDo.Worker/Report/WeekReportService.cs

@@ -69,7 +69,12 @@ public sealed class WeekReportService : IWeekReportService
             // alphanumerics, dashes and dots only.
             var safeModel = new string(model.Where(c => char.IsLetterOrDigit(c) || c is '-' or '.').ToArray());
             if (safeModel.Length == 0) safeModel = "sonnet";
-            var args = $"-p --output-format stream-json --verbose --permission-mode auto --model {safeModel}";
+            IReadOnlyList<string> args =
+            [
+                "-p", "--output-format", "stream-json", "--verbose",
+                "--permission-mode", "auto",
+                "--model", safeModel,
+            ];
             var result = await _claude.RunAsync(args, prompt, Path.GetTempPath(), _ => Task.CompletedTask, ct);
             if (!result.IsSuccess)
                 throw new InvalidOperationException(result.ErrorMarkdown ?? "Claude could not generate the report.");