chore: add vision tool and Claude Code skill for UI screenshot review

- scripts/vision.py: call MiMo v2.5 via Anthropic-format API for image analysis
- scripts/screenshot_mission_list.py: Playwright screenshot of /missions page
- .claude/skills/vision.md: Claude Code skill for vision task delegation

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.claude/skills/vision.md

@@ -0,0 +1,45 @@
+---
+name: vision
+description: Use when you need to visually inspect a screenshot, UI render, or any image — the current model has no multimodal capability, so vision tasks MUST be delegated to this tool.
+---
+
+# Vision Tool
+
+When you need to look at an image (screenshot, UI render, diagram, photo), call the MiMo v2.5 multimodal model via this script.
+
+## Usage
+
+```bash
+python scripts/vision.py "<image_path>" "<question>"
+```
+
+## When to Call
+
+You MUST use this for any of the following:
+- Checking a UI screenshot for layout issues (overlapping elements, overflow, alignment)
+- Verifying a page render looks correct after a change
+- Reading text or data from a screenshot
+- Analyzing any image the user provides
+- Any task where you think "I wish I could see this"
+
+## Examples
+
+```bash
+# Basic UI inspection
+python scripts/vision.py "demo/test_screenshots/timeline_page.png" \
+  "Check this timeline page for any UI issues: overlapping elements, clipped text, misaligned segments. Report each issue with its location."
+
+# Comparing two screenshots
+python scripts/vision.py "demo/test_screenshots/docking_modal.png" \
+  "Is the docking modal properly centered? Are all buttons visible and correctly labeled? Is the datetime input functional-looking?"
+
+# Reading wiki page render
+python scripts/vision.py "data/KSP/Vulture Shuttle Full Stack at Launch Pad.png" \
+  "Describe what you see in this image in detail."
+```
+
+## Notes
+
+- Images over ~5 MB may be slow; consider resizing large screenshots first
+- The MiMo model runs remotely — no local GPU needed
+- Response is text-only; the model describes what it sees