fix(memory): allow desktop distillation requests

[SunwardL]

Fix desktop Memory distillation IPC routes

Summary

• Allow the desktop runtime IPC bridge to forward the Memory distillation candidate collection request and individual candidate decision request.
• Keep the allowlist narrow: only GET /v1/memory/distillation and POST /v1/memory/distillation/:candidateId/decision are admitted.
• Add focused regression coverage for allowed methods, rejected methods, malformed nested paths, and unchanged Memory record/diagnostics routes.
• Record the historical interactive acceptance finding in the active Memory distillation OpenSpec change.

Why

PR #1266 added the runtime and renderer-side Memory distillation flow, but the desktop IPC request schema did not include its two endpoints. The renderer therefore could construct candidate-list and Allow/Deny/Withdraw requests, while the Electron main-process allowlist rejected them before they reached the Kun runtime.

The explicit distillation templates are registered before the generic /v1/memory/{id} matcher. This preserves the existing record mutation contract and avoids treating distillation as a Memory record ID.

Changes

• Import and register the existing distillation collection and decision endpoint templates in src/main/ipc/app-ipc-schemas/runtime.ts.
• Add 17 tests in src/main/ipc/app-ipc-schemas-memory-distillation.test.ts.
• Preserve the OpenSpec distinction between the historical blocked UI run and acceptance that still needs to be repeated on the current baseline.

Tests

• Focused Vitest: 65/65 passed
  • Memory distillation IPC: 17/17
  • Existing app IPC schema: 37/37
  • Kun runtime config service: 11/11
• npm run typecheck
• npm run build
• npm run lint — 0 errors, 30 existing warnings
• openspec validate add-kun-memory-distillation --strict
• git diff --check

The full local test suite and packaging matrix were not rerun for this three-file patch; PR CI remains the source of truth for those broader checks.

Related: #1266