[0.6] refactor(ipc): extract registerCommand wrapper + migrate notes handlers

[h4yfans]

Summary

Unit 0.6 of the IPC tech-debt cleanup. Extracts the repeated triple-nested IPC handler registration pattern into a single registerCommand helper and migrates the qualifying notes handler sites to use it.

What changed

• New: apps/desktop/src/main/ipc/lib/register-command.ts — registerCommand(channel, schema, command, fallback?) composes createValidatedHandler + withErrorHandler + ipcMain.handle in a single call. Handler callback retains full control over its return shape; no envelope is imposed.
• New: apps/desktop/src/main/ipc/lib/register-command.test.ts — 5 tests covering registration, validated input forwarding, schema rejection, thrown-error envelope, fallback message.
• Migrated 15 handler sites in apps/desktop/src/main/ipc/notes-handlers.ts:
  • create, update, rename, move
  • rename-folder
  • create-property-definition, update-property-definition
  • delete-attachment, set-folder-config
  • export-pdf, export-html
  • get-positions, reorder, import-files, set-local-only
• Untouched (as specified): handlers using createHandler (no input) or createStringHandler (bare string input), and bare createValidatedHandler calls without nested withErrorHandler.

Line deltas

• notes-handlers.ts: 951 → 942 (-9 net, diff shows +236 / -249 of migrated content)
• Still over the 800-line guideline; splitting the file is out of scope for this refactor (would block on deciding handler grouping and would touch unrelated surface area).

IPC generator updates

The migration caused two regressions in generated-ipc-invoke-map.ts that had to be fixed in scripts/generate-ipc-invoke-map.js:

1. Migrated channels were dropped because the scanner only looked for literal ipcMain.handle(...) calls. Added detection for registerCommand(...).
2. Input type narrowed incorrectly. The old pipeline typed the IPC boundary via rawInput: z.input<TSchema> (defaulted fields optional). With registerCommand, the command callback is typed (input: z.infer<TSchema>) => TResult (defaulted fields required), which narrowed the boundary type and broke callers. Generator now reads z.input from the schema's own type via its _input property for registerCommand calls, matching previous semantics.
3. Return type was losing the { success: false; error: string } branch that withErrorHandler adds at runtime. Generator now unions that branch into the awaited return for registerCommand calls, matching the previous union shape.

E2E smoke

pnpm test:e2e -- --grep "note" was launched but did not complete end-to-end within the available run window (Playwright was still iterating through body-crdt-*, note-sync-helpers, and notes.e2e.ts suites after ~10 minutes with no failures reported, then stopped producing new artifacts with no output written to stdout). The run was terminated without a full pass/fail summary. Cannot confirm e2e end-to-end.

Instead, the final npx electron-vite build succeeded cleanly — evidence below (last 20 lines):

../../out/renderer/assets/c-Bl5xafGJ.js                                               86.65 kB
../../out/renderer/assets/swift-Cohr-WZC.js                                           86.72 kB
../../out/renderer/assets/markdown-C7dg6S-0.js                                        88.93 kB
../../out/renderer/assets/latex-BmLmUh3i.js                                           97.40 kB
../../out/renderer/assets/less-zLwf3ygQ.js                                           116.23 kB
../../out/renderer/assets/objective-c-BTI_-NdD.js                                    118.78 kB
../../out/renderer/assets/php-RZFa1R9o.js                                            122.85 kB
../../out/renderer/assets/react-BQmmxN09.js                                          124.55 kB
../../out/renderer/assets/csharp-C-3Z-GKA.js                                         131.37 kB
../../out/renderer/assets/mdx-CAb1w3A_.js                                            181.53 kB
../../out/renderer/assets/javascript-S2Lhd_8f.js                                     205.60 kB
../../out/renderer/assets/tsx-_uqdJL1n.js                                            206.31 kB
../../out/renderer/assets/jsx-Bc8fwi-X.js                                            208.56 kB
../../out/renderer/assets/typescript-pLKQCwWX.js                                     212.27 kB
../../out/renderer/assets/index-CxAH9-ZR.js                                          778.83 kB
../../out/renderer/assets/cpp-D70-f36R.js                                            897.48 kB
../../out/renderer/assets/hls-BmqwCFVH.js                                          1,115.49 kB
../../out/renderer/assets/dash.all.min-Ms6H1cSG.js                                 1,306.00 kB
../../out/renderer/assets/index-I0IF_00U.js                                       16,085.02 kB
✓ built in 17.07s

Verification

• pnpm ipc:check - pass
• pnpm lint - 0 errors, 1420 pre-existing warnings (none introduced by this PR in notes-handlers.ts)
• pnpm --filter @memry/desktop typecheck:node - pass
• pnpm --filter @memry/desktop typecheck:web - pass
• pnpm typecheck:packages - pass (FULL TURBO)
• pnpm test - 5691/5692 pass; single failure is the known calendar-page.test.tsx:258 "Due draft" flake
• npx electron-vite build - pass
• New register-command.test.ts - 5/5 pass

Test plan

• Create, update, rename, move a note through the app
• Create and update property definitions (text, select, status)
• Delete an attachment
• Set/rename/delete a folder config
• Export a note to PDF and HTML (including cancel dialogue path)
• Reorder notes in a folder
• Import files into the vault
• Toggle local-only flag on a note