fix: resume BLOCKED tasks in preserved sandbox so Claude finds its session

When a task ran in a sandbox (/tmp/claudomator-sandbox-*) and went BLOCKED,
Claude stored its session under the sandbox path as the project slug. The
resume execution was running in project_dir, causing Claude to look for the
session in the wrong project directory and fail with "No conversation found".

Fix: carry SandboxDir through BlockedError → Execution → resume execution,
and run the resume in that directory so the session lookup succeeds.

- BlockedError gains SandboxDir field; claude.go sets it on BLOCKED exit
- storage.Execution gains SandboxDir (persisted via new sandbox_dir column)
- executor.go stores blockedErr.SandboxDir in the execution record
- server.go copies SandboxDir from latest execution to the resume execution
- claude.go uses e.SandboxDir as working dir for resume when set

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

1 files changed, 3 insertions, 1 deletions

diff --git a/internal/api/server.go b/internal/api/server.go
index 944e450..c545253 100644
--- a/internal/api/server.go
+++ b/internal/api/server.go
@@ -260,12 +260,14 @@ func (s *Server) handleAnswerQuestion(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	// Submit a resume execution.
+	// Submit a resume execution. Carry the sandbox path so the runner uses
+	// the same working directory where Claude stored its session files.
 	resumeExec := &storage.Execution{
 		ID:              uuid.New().String(),
 		TaskID:          taskID,
 		ResumeSessionID: latest.SessionID,
 		ResumeAnswer:    input.Answer,
+		SandboxDir:      latest.SandboxDir,
 	}
 	if err := s.pool.SubmitResume(context.Background(), tk, resumeExec); err != nil {
 		writeJSON(w, http.StatusServiceUnavailable, map[string]string{"error": err.Error()})