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.

electron/main.cjs

@@ -36,6 +36,14 @@ const path = require("node:path");
 const SIDEBAR_AUTOCLOSE = 928;
 
 const PRODUCT_NAME = "LearnHarness";
+
+// APP NAME → userData (owner, 2026-10-10): the Application Support dir is
+// exactly "LearnHarness" in dev AND packaged. Packaged Electron would
+// otherwise derive it from package.json "name" (now lowercase
+// "learnharness"), and productName metadata alone doesn't reach app.name.
+// Must run before the LH_DEV_URL suffix below — dev becomes
+// "LearnHarness-dev".
+app.setName(PRODUCT_NAME);
 const AUTH_FILE = () => path.join(app.getPath("userData"), "auth.json");
 const DATA_DIR = () => path.join(app.getPath("userData"), "data");