feat(config): real config reset/repair + migration framework (drop manual-delete) (#38)

Eliminates the fragile "delete the config folder before upgrading" tester
instruction, which was wrong-by-OS because the userData folder name was
derived inconsistently per platform (fee[dB]ack on macOS, slopsmith-desktop
on Linux/Windows).

A. Deterministic paths + migration framework
- Pin the userData name on every OS via app.setName('feedback-desktop') +
  build.extraMetadata.name; brand (productName 'fee[dB]ack') unchanged.
- One-time userData migration copies a legacy folder into the new one so
  upgraded users don't start fresh (atomic copy-then-rename, fail-soft).
  Runs before the single-instance lock / crashReporter, which would otherwise
  create userData and defeat the "new dir doesn't exist" gate.
- config-migrations.ts: versioned, ordered, idempotent, fail-soft migration
  runner stamped in CONFIG_DIR/config_version.json; logs the active CONFIG_DIR
  at startup (closes the Linux ~/.local/share/slopsmith shared-config gap).

B. In-app "Reset / repair configuration" (Settings panel)
- Granular options: reset app settings & caches, clear plugin state & cached
  Python deps, and full reset with default-OFF opt-ins for installed plugins /
  song library / ML caches.
- config-paths.ts is the single source of truth for per-OS path enumeration;
  the song library, installed plugins and ML caches are structurally confined
  to optInExtras and never wiped by the safe/full categories.
- Reset stops the backend, deletes immediate paths, includes SQLite WAL/SHM
  sidecars + the migration stamp on full reset, and defers Chromium/Crashpad
  state to next launch (consumed before any window reopens it). ML caches honor
  TORCH_HOME/HF_HOME. Empty selection is a no-op (backend left running).
- SECURITY: destructive resets require a native main-process confirmation
  dialog — the renderer bridge is reachable by plugin scripts, so a
  renderer-only confirm is not a sufficient gate.

Tests: node:test suites for path enumeration (per-OS + library/plugins
preserved), migration idempotency/fail-soft, reset delete pipeline guarantees,
userData migration, and deferred-deletion schedule/consume. `npm test` green
(adds a test script). codex review --base origin/main clean.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/_load-ts.js

@@ -0,0 +1,30 @@
+// Shared helper: compile a TypeScript module on the fly and load it as CommonJS,
+// matching the transpile-on-load pattern used by the other node:test suites
+// (see audio-effects-executor.test.js). Lets us unit-test the pure config-*.ts
+// modules without a build step or an electron runtime.
+const fs = require('node:fs');
+const path = require('node:path');
+const Module = require('node:module');
+const ts = require('typescript');
+
+const ROOT = path.join(__dirname, '..');
+
+function loadTs(relPath) {
+    const file = path.join(ROOT, relPath);
+    const source = fs.readFileSync(file, 'utf8');
+    const compiled = ts.transpileModule(source, {
+        compilerOptions: {
+            module: ts.ModuleKind.CommonJS,
+            target: ts.ScriptTarget.ES2022,
+            esModuleInterop: true,
+        },
+        fileName: file,
+    }).outputText;
+    const mod = new Module(file, module);
+    mod.filename = file;
+    mod.paths = Module._nodeModulePaths(path.dirname(file));
+    mod._compile(compiled, file);
+    return mod.exports;
+}
+
+module.exports = { loadTs, ROOT };