Search and filter nodes (by name, epic, tag, role)（节点搜索 / 过滤）

[Kaka-cheaper]

Goal

Add a search box that filters nodes on the canvas: type "login" → only login-related nodes stay visible, others fade out.

Why

40+ feature projects (like the Polisim test case) need fast lookup. Scrolling the canvas to find a feature is slow.

Scope (what is in)

• Search box in TopBar (or a / keyboard shortcut to focus)
• Live filter as user types: matches name, summary, tags, epicId
• Non-matching nodes fade to 18% opacity (reuse the existing hover-dim mechanism)
• Edges where neither endpoint matches also fade
• Empty query → reset
• Esc clears the search
• Result count shown next to the box (e.g. "3 matches")

Out of scope

• Regex search (just substring match)
• Search within step.note (do in follow-up)
• Persistent filters across page reload

Files likely involved

• viewer/src/app/TopBar.tsx (search input)
• viewer/src/graph/GraphCanvas.tsx (apply dim based on search match)
• viewer/src/lib/i18n.ts (placeholder text)

Acceptance criteria

• Typing in the search box dims non-matching nodes within 100ms
• Esc / clear button restores all nodes
• Works in all three views (overview, features, steps)
• Match count visible

Estimated effort

~4-5 hours / ~3 files

Hints

Look at how hoverId and focusId already produce a dimmed set in GraphCanvas. Plug a "search match set" into the same mechanism.

Want to take this?

Comment "I'd like to take this" and I'll confirm within 24h.