repo: public housekeeping — license, product name, docs diet

- LICENSE: AGPL-3.0-only (holder Amos Blomqvist), package.json gains "license".
- Product/package name unified: package.json "name" is now "learnharness"
  (matches the GitHub repo); electron-builder productName/appId already
  were LearnHarness/com.learnharness.LearnHarness.
- Deterministic userData: app.setName("LearnHarness") early in main.cjs
  — Application Support dir is exactly "LearnHarness" in dev and
  packaged runs (packaged Electron would otherwise derive it from the
  package name). Dev shell becomes "LearnHarness-dev". Pre-release
  rename: zero external users, no migration code; the local test dir
  was moved by hand.
- docs/ diet: nine vision-*.md splinters, the completed pi-ai migration
  plan, and research/ notes leave the tree (retained privately in the
  git-ignored memory; full history stays in git). Public docs remain:
  architecture, vision, plan, probe-teach-split, pi-engine-swap,
  keyboard, teaching-methodology (+ release-0.3 until the ship).

Gates: 1489/1489, typecheck, lint.

package.json

@@ -1,6 +1,7 @@
 {
-	"name": "learning-harness",
+	"name": "learnharness",
 	"version": "0.2.0",
+	"license": "AGPL-3.0-only",
 	"description": "A standalone learning harness: a teacher agent (AI SDK) with quiz/ask interactions, session artifacts, and a derived knowledge graph of what the learner knows.",
 	"type": "module",
 	"private": true,