Add configurable working directory for dev server scripts (Vibe Kanban) (#1559)

* The implementation is complete. Here's a summary of all the changes made:

## Summary

Added the ability for users to specify a working directory for dev server scripts:

### Files Changed:

1. **Database migration** - `crates/db/migrations/20251216000000_add_dev_script_working_dir_to_projects.sql`
   - Added `dev_script_working_dir TEXT DEFAULT ''` column

2. **Rust model** - `crates/db/src/models/project.rs`
   - Added `dev_script_working_dir` field to `Project` and `UpdateProject` structs
   - Updated all SQL queries

3. **Dev server execution** - `crates/server/src/routes/task_attempts.rs`
   - `start_dev_server` now passes `project.dev_script_working_dir` to the script executor

4. **Backfill logic** - `crates/services/src/services/container.rs`
   - Changed `backfill_repo_names` to set `dev_script_working_dir` instead of prepending `cd ./repo &&`

5. **Frontend UI** - `frontend/src/pages/settings/ProjectSettings.tsx`
   - Added input field for "Dev Server Working Directory"

6. **Translations** - `frontend/src/i18n/locales/en/settings.json`
   - Added `devWorkingDir` label, placeholder, and helper text

7. **TypeScript types** - `shared/types.ts`
   - Regenerated with `dev_script_working_dir` field

* Cleanup script changes for task attempt 83423e2d-0d45-47fb-a6e4-dd91a2140f91

* Both packages compile successfully. The fix is complete:

1. **`project.rs`**: Removed `.or()` fallback for `dev_script` and `dev_script_working_dir` so `None` now clears the field
2. **`container.rs`**: Updated backfill to explicitly pass the existing project name instead of `None`

* Done. I've completed both review tasks:

1. Removed the comment from `container.rs` line 384
2. Added `devWorkingDir` translations to all four language files (es, ja, ko, zh-Hans) with:
   - `label`: The field label
   - `placeholder`: Example placeholder text
   - `helper`: Description of what the field does

I also updated the `dev.helper` text in each language to reference the new working directory option instead of suggesting users manually `cd` into the repo directory.

* Done. Removed both comments:
1. Removed the comment from the migration file
2. Removed the comment from `task_attempts.rs` line 1267

* Fixed. The TypeScript error in `NoServerContent.tsx` has been resolved by adding `dev_script_working_dir: null` to the `UpdateProject` data. All checks pass:

- ✅ `npm run format` - completed
- ✅ `npm run lint` - passed (frontend and backend)
- ✅ `npx tsc --noEmit` - passed

* The Korean and Chinese translations already had the updated copy without the `cd` reference. The Spanish and Japanese were updated. All the translations now have the proper helper text that references the working directory field instead of telling users to manually `cd` into the repo.

* Done. I've removed the `cd my_website` line from both the Windows and Unix script placeholder examples in `scriptPlaceholders.ts`. Now the placeholder examples just show `npm run dev` without the `cd` command, since users can specify the working directory separately.

crates/services/src/services/container.rs

@@ -343,7 +343,7 @@ pub trait ContainerService {
     }
 
     /// Backfill repo names that were migrated with a sentinel placeholder.
-    /// Also backfills dev_script for single-repo projects to prepend cd prefix.
+    /// Also backfills dev_script_working_dir for single-repo projects.
     async fn backfill_repo_names(&self) -> Result<(), ContainerError> {
         let pool = &self.db().pool;
         let repos = Repo::list_needing_name_fix(pool).await?;
@@ -364,22 +364,30 @@ pub trait ContainerService {
 
             Repo::update_name(pool, repo.id, &name, &name).await?;
 
-            // Also update dev_script for single-repo projects
+            // Also update dev_script_working_dir for single-repo projects
             let project_repos = ProjectRepo::find_by_repo_id(pool, repo.id).await?;
             for pr in project_repos {
                 let all_repos = ProjectRepo::find_by_project_id(pool, pr.project_id).await?;
                 if all_repos.len() == 1
                     && let Some(project) = Project::find_by_id(pool, pr.project_id).await?
-                    && let Some(old_script) = &project.dev_script
-                    && !old_script.is_empty()
+                    && project
+                        .dev_script
+                        .as_ref()
+                        .map(|s| !s.is_empty())
+                        .unwrap_or(false)
+                    && project
+                        .dev_script_working_dir
+                        .as_ref()
+                        .map(|s| s.is_empty())
+                        .unwrap_or(true)
                 {
-                    let new_script = format!("cd ./{} && {}", name, old_script);
                     Project::update(
                         pool,
                         pr.project_id,
                         &UpdateProject {
-                            name: None,
-                            dev_script: Some(new_script),
+                            name: Some(project.name.clone()),
+                            dev_script: project.dev_script.clone(),
+                            dev_script_working_dir: Some(name.clone()),
                         },
                     )
                     .await?;