Desktop: WSL section missing entirely from environment picker on new session screen (regression after update to 1.49585.0)

## Description

The **WSL section is completely missing** from the environment picker on the "New session" (새로 생성) home screen in Claude Desktop's Code tab, even though WSL 2 with an installed distribution meets all documented requirements. Only **Local / Cloud / Remote Control / SSH** appear — no WSL section at all.

This appears to be a regression introduced by an app auto-update that happened this morning.

## Environment

- Desktop app version: was `1.46388.4`, auto-updated to **`1.49585.0`** at **2026-09-09 04:38** (local time), per `main.log`:
```
2026-09-09 04:37:03 [info] [updater] Staged version 1.49585.0 is still current (latest: 1.49585.0, lastTarget: null)
2026-09-09 04:38:17 [info] [updater] Version changed since last launch: 1.46388.4 -> 1.49585.0
```
- In-app CCD version: `2.1.260`
- OS: Windows 11 Pro (10.0.26200)
- WSL distro: Ubuntu, WSL version 2, `git version 2.43.0` installed inside the distro (requirement met)
- `wsl --list -v` confirms the distro is installed and running; `wsl --list -v` / `wsl -l -v` respond in ~200ms (not a detection timeout)

## Requirements per docs (all met)

Per https://code.claude.com/docs/en/desktop-wsl.md:
- Windows 10/11 with WSL 2 ✅ (WSL 1 not installed/used)
- At least one installed distribution ✅ (Ubuntu)
- `git` installed inside the distribution ✅

## Repro steps

1. Update Claude Desktop to `1.49585.0` (or later, if the regression persists) on Windows with WSL 2 + a distro already installed and previously used successfully.
2. Click "새로 생성" ("Create new" / new session) in the Code tab sidebar.
3. Open the environment picker (the dropdown above the composer).
4. **Actual**: Only "로컬" (Local), "클라우드" (Cloud), "원격 제어" (Remote Control), "SSH" are listed. No "WSL" section.
5. **Expected**: A "WSL" section listing installed WSL 2 distributions (e.g. "Ubuntu"), per the documented behavior.

## Notes / what still works

- Existing/previously-created sessions bound to WSL (opened via the sidebar's in-progress items rather than through the "새로 생성" environment picker) continue to work fine and are actively used post-update — `main.log` shows `LocalSessions.getRemoteGitInfo: target=wsl:Ubuntu, ...` and even a brand-new spawn (`[SSH] Using remote spawn function for session ... on wsl:Ubuntu`) as recently as `2026-09-09 13:59:53`, all *after* the update. So WSL execution itself still works — only the **environment picker on the fresh "new session" screen** fails to surface the WSL option.
- This looks distinct from #92928 (WSL project "+" button opens generic New view without pre-filling the folder), which was filed against the older `1.46388.4` build and describes a different symptom (folder not pre-filled, vs. WSL section absent entirely).

## Impact

Cannot start a brand-new WSL session from scratch via the normal "새로 생성" flow; only continuing existing WSL-bound sessions works.

Start by reproducing the new-session environment picker on Windows 11 with WSL 2 and an Ubuntu distro, using the documented requirements in the issue. Compare the path that populates Local/Cloud/Remote Control/SSH with the path still used by existing WSL-bound sessions. Done means the picker again shows a WSL section with installed distributions while existing session behavior remains working.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.