Update roadmap: Phases 15-18 + Round 5 research (50 sources)

- Phase 15: Editor DX (GM_* IntelliSense, auto-grant AST, version
  history w/ diff-match-patch, diff-on-update, templates, esbuild-wasm
  TS transpilation, live reload, dry-run sandbox)
- Phase 16: Advanced XHR (GM_fetch, AbortController, streaming,
  CHIPS cookiePartition, redirect mode, GM_download Blob, OpenUserJS)
- Phase 17: Security Round 2 (body integrity hash, tamper-evident
  audit log, update consent decoupling, message origin validation,
  @require-css, GM_addStyle handle API + ShadowRoot)
- Phase 18: Performance (ES module split, OPFS, scheduler.postTask,
  CompressionStream, TanStack Virtual, SharedWorker extendedLifetime,
  Sanitizer API GM_setHTML, storage.persist(), broken script detector,
  @require-nocache)
- Update dependency diagram and execution order (steps 17-20 added)
- Add v4.5-v4.8 version mapping for Phases 15-18
- Round 5 External Research: sources 47-96 (50 new citations)
- Update Chrome API Timeline: Chrome 146-150 entries
- Extend Feature Harvest appendix: Phases 15-18 accepted rows + new
  rejected items (AI Agent, GM_webRequest, full OPFS migration,
  ClickRemix, GM_wsConnectTo)

Author: SysAdminDoc