feat(desktop): Add image export modes and fix Windows file reveal

[wsp1911]

Summary

• Add a menu to the conversation image export button with two options:
  • Compact image: keep thinking headers and collapse their content.
  • Image with thinking: include the full thinking content.
• Fix Windows file reveal opening the wrong directory for filenames containing spaces.
• Update English, Simplified Chinese, and Traditional Chinese labels.

Type and Areas

Type: Feature / bug fix / UI/UX

Areas: Desktop/Tauri, Web UI, i18n

Motivation / Impact

Image exports previously always included expanded thinking content.
Users can now choose a compact image for sharing or include the full
thinking content.

On Windows, the previous implementation passed /select, and the file
path as one command-line argument. Paths containing spaces caused the
entire argument to be quoted, which could make Explorer open its default
directory instead of selecting the exported file.

File reveal now uses the existing tauri-plugin-opener integration,
which resolves files through the Windows Shell API.

Verification

Passed:

• pnpm run type-check:web
• pnpm --dir src/web-ui exec tsc --noEmit
• pnpm --dir src/web-ui exec eslint src/flow_chat/components/modern/ExportImageButton.tsx
• pnpm run i18n:audit
• pnpm run theme:color-audit:all
• pnpm run fmt:rs
• git diff --check

Additional verification:

• pnpm run motion:audit completed as an inventory check, not a pass/fail gate.
• Two temporary, non-UI Windows Shell tests passed. They verified that
  the actual exported image and filenames containing spaces, Chinese
  characters, brackets, dollar signs, and commas resolve to the correct
  filesystem paths. The diagnostic program is not included in this PR.
• cargo check -p openbitfun-desktop was stopped while waiting for a
  build lock held by another build; compilation verification is incomplete.
• UI interaction, actual Explorer file selection, macOS/Linux runtime
  behavior, and remote scenarios were not exercised.

Reviewer Notes

• Exploration grouping and tool-card export behavior remain unchanged.
  “Image with thinking” does not expand all tool details.
• The Windows fix applies to the shared file-reveal function and benefits
  other callers as well.
• Directory opening and the macOS/Linux implementations remain unchanged.
• No persistence changes, protocol changes, or data migrations are involved.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are updated where applicable.