feat(ask-code): send attached images to an image-capable MiniMax model

[octo-patch]

Reason: The inline code Q&A already resolves pasted images to temp file paths, but the MiniMax provider could only send a text prompt, so an attached image never reached a model that accepts image input.

What changed

• electron/ipc/ask-code-minimax.ts — a request can now carry imagePaths. When images are attached, the user message is sent as content parts (a text part plus one image_url data URL per image) instead of a plain string, and the request is routed to a model whose catalog input modalities include images (MiniMax-M3, which accepts text, image and video input). MiniMax-M2.7 is text-only and stays the default for text questions, so text-only requests send exactly the same payload as before. Image input is validated and capped separately from the 50,000-character prompt limit, since the bytes never count against it: at most 4 images per question, 10 MB each, .png / .jpg / .jpeg / .webp / .gif. Unsupported or excessive input is rejected before a request slot is taken, and an unreadable file is reported on the response channel.
• electron/ipc/ask-code.ts, electron/ipc/register.ts — forward the new imagePaths argument and validate it, running every entry through the existing absolute-path check. The other Q&A backend is unchanged and still receives a text prompt only.
• src/components/InlineInput.tsx — pasting an image into the inline Ask input attaches it, reusing the existing resolve_clipboard_paste handler that the terminal already uses, so no new IPC channel is added. The affordance is only active in Ask mode while the MiniMax provider is selected, and a small chip shows the attachment and clears it.
• src/components/ReviewProvider.tsx, src/components/ScrollingDiffView.tsx, src/components/PlanViewerDialog.tsx, src/components/AskCodeCard.tsx — thread the attached paths from the inline input through the question to the request. Both Ask surfaces share the same input, so both gain the capability.

New tests in electron/ipc/ask-code-minimax.test.ts cover the model modality lookup, the unchanged text-only payload, image parts sent as data URLs to the image-capable model, a rejected image type, the per-question image cap, and an unreadable image surfacing as an error without a request being sent.

Checks

• npx vitest run — 115 files passed, 1873 tests passed, 22 skipped
• npx vitest run --config vitest.client.config.ts — 2 files passed, 9 tests passed
• npx tsc --noEmit and npx tsc -p electron/tsconfig.json — clean
• npx eslint . --max-warnings 0 — clean
• npx prettier --check . — clean
• npm run lint:arch — no dependency violations
• npm run lint:dead — clean