docs(FR-2571): address PR #6631 review feedback (excl. model store) (#6708)

Resolves #6675 follow-up — Addresses review feedback on PR #6631 (model-store items intentionally excluded).

Stacked on top of PR #6631 (`04-13-docs_header_add_allowed_client_ips_field_to_my_account_dialog_documentation`).

## Changes

### Text edits (applied identically across en/ko/ja/th)
- **header/header.md**: Replaced "when the server supports the V2 user update API" phrasing in both the **Allowed Client IPs** note and the **Original password** note with explicit version gating — *"Backend.AI 26.4.0 and later"*.
- **vfolder/vfolder.md §10.1**: Clarified that for project folders, the project currently selected in the top bar is automatically selected as the target. (Model-type project-folder sentence intentionally **excluded**.)
- **vfolder/vfolder.md `write_content`**: Rewrote the File Edit button permission description — it is a per-folder (vfolder) RBAC permission granted via folder sharing or role, **not** a storage-host setting. Verified against `react/src/components/FolderExplorerModal.tsx` (reads `vfolder_node.permissions`).
- **vfolder/vfolder.md §10.3**: Folder rename is now described as available only inside the folder detail drawer (removed "from the Controls column").
- **vfolder/vfolder.md §10.7**: Removed the empty *Folder Categories* H2 heading.
- **overview/overview.md §3.3**: Added a **Project** row to the "Accessible Menu by User Role" table.

### Screenshots recaptured (captured in English UI, copied to all 4 language `images/` dirs)
- `header.png` — top bar **including visible Login Session Timer** (Fig 6.1)
- `menu_collapse.png` — sidebar without customer-specific plugin entries (Fig 7.2)
- `data_page.png` — folder list with **Controls column merged into Name** (Fig 10.1 / §10.4)
- `vfolder_create_modal.png` — current folder-creation modal
- `rename_vfolder.png` — rename UI **inside the detail drawer**
- `move_to_trash.png` — new **Modal** confirmation (replaces Popconfirm)
- `vfolder_delete_dialog.png` — current Delete Forever modal
- `sessions_page.png` — current Sessions page layout (Fig 11.1)
- `launch_session_resource_2.png` — Cluster Mode launcher step
- `launch_session_data.png` — Data & Storage launcher step

### Explicitly excluded (per request)
- All model-store-related items:
  - *"Model-type project folders can only be created within projects designated as model store projects"* (§10.1 item #2)
  - *"Run directly using the `deploy` button"* (model store §26.4.0 content)

### Deferred (out of scope)
- Per-language localized screenshot policy (reviewer request conflicts with current `SCREENSHOT-GUIDELINES.md` — recommended to change policy in a follow-up PR).
- Pre-existing untranslated English blocks in `ja/` and `th/` `sessions_all.md` and `vfolder.md` §10.1 bullets — flagged by reviewer, not touched in this PR.

## Agent workflow

Generated via `fw:docs-planner` → `fw:docs-writer` → screenshots captured via Chrome DevTools MCP → `docs-update-reviewer` cross-language + cross-page link review (MINOR FIXES APPLIED). Agent artifacts: `.agent-output/docs-update-plan-pr6631-review.md`, `.agent-output/docs-review-report-pr6708-cross-lang-and-links.md`.

Reviewer auto-fixes:
- Corrected broken image reference `launce_session_resource_2.png` → `launch_session_resource_2.png` in all 4 `sessions_all.md` (pre-existing typo, made load-bearing by this PR recapturing the file).
- Collapsed stray double blank line before `:::note` block after Cluster mode bullet.

**Checklist:**
- [x] Documentation
- [x] Structural parity across en/ko/ja/th verified
- [x] Cross-page links and image references verified
- [x] No model-store content introduced

Author: nowgnuesLee

.claude/agents/docs-screenshot-capturer.md

@@ -56,5 +56,9 @@
       },
       "inputs": [],
     },
+    "i18n-ally.localesPaths": [
+      "resources/i18n",
+      "packages/backend.ai-ui/src/locale",
+    ],
   },
 }