fix: palette-add mints unique node ids against live topology

[Dahhrk]

What this changes

Palette-add (handleAddNode) now mints node ids against the live topology mirror instead of a module counter that resets on page load. Closes xevrion#46.

Why

makeNode uses a module-level nodeCounter that resets on load. Two palette-adds of the same kind mint the same id. isTopology rejects the save, and loadSession silently falls back to PRESETS[0].

Changes

• src/clipboard.ts: export freshId (contract unchanged)
• src/App.tsx: handleAddNode reads topoLiveRef.current (not the React topology closure), overrides id with freshId, and drops topology from the dependency array. Two rapid adds no longer drop the first node.
• src/clipboard.test.ts: freshId unit tests (unique mints, skip-existing, isTopology accepts)
• src/handleAddNode.wiring.test.ts (new):
  • Source wiring assertion: handleAddNode spreads topoLiveRef.current, not the React topology binding; freshId is called; topology is not in the dep array.
  • Behavioral test: two sequential cache adds against the default preset (client, api, db) with no intervening render. Both nodes survive, ids are unique, isTopology accepts.

Verification

$ bun run test
 Test Files  37 passed (37)
      Tests  904 passed (904)

$ bun run build   # tsc -b && vite build
✓ clean

$ bun run lint
Pre-existing warnings only, no new issues.

• bun run test passes (904 tests, 37 files)
• bun run typecheck and bun run lint pass
• bun run build passes
• Screenshot attached, if anything visual changed

GitHub CI

No GitHub Actions check_runs exist on this repo. The only status is Vercel deployment, which reports "Authorization required to deploy" (not a CI gate, not proof of correctness).

GET /repos/xevrion/breakscale/commits/0a76206/check-runs → {"total_count": 0, "check_runs": []}
GET /repos/xevrion/breakscale/commits/0a76206/statuses → [{"context": "Vercel", "state": "failure", "target_url": "…/authorize…"}]

Keep

• Draft only. Author does not merge.
• No issue comment beyond this PR linking Adding a component from the rail can mint a duplicate id, and the next reload silently discards the design xevrion/breakscale#46.
• One verifiable unit.

Upstream PR (same branch): xevrion#47