emrg: gui renderer Batch 5 final switch — main.js loads React renderer dist

[argszero]

The Batch 5 final switch (part 1): production GUI now runs the React renderer.

Changes:

• emrg/gui/main.js: both loadFile calls (initial load + render-process-gone reload) now point to renderer/dist/index.html instead of the vanilla renderer/index.html.
• Agent.md: Batch 5 bullet updated (final switch part 1; vanilla files retained for revert).

Context:

• emrg: gui renderer Batch 5 final-switch CI prep — build renderer/dist in release pipeline #1022 already added the Vite renderer build step to the release pipeline (build-release.yml) and removed the dist exclusion from the electron-builder files whitelist, so renderer/dist is now built + packaged on all 4 release runners.
• The React app is self-contained (own shell.css bundled into dist/assets/*.css); dist/index.html uses CSP-safe relative assets (Vite base './').
• Vanilla renderer files (renderer/js, renderer/css, renderer/index.html) and the vm.runInContext smoke tests are deliberately KEPT in this PR for instant revert — they become inert; a follow-up cleanup PR removes them (design doc D6).
• preload.js bridge (52 invoke + onEvent) untouched; React components use the same window.emrg surface.

Verification: pytest 1106+1, GUI 265 (257 pass/0 fail), renderer typecheck + vite build → dist/index.html present, import + CLI OK, doc-count 4/4, actionlint clean (no workflow change).

[argszero]

✅ LGTM — cycle 2026-08-27T03:37:50

Independent review of the full diff (head 46edc0a, after the prestart addition):

• main.js: both loadFile calls (initial window + render-process-gone reload) now point to renderer/dist/index.html — consistent with the #1022 pipeline change that builds + whitelists dist.
• gui package.json: added prestart → npm --prefix renderer run build, so the documented npm start flow works on a fresh clone (dist is gitignored; previously a fresh npm start would white-screen). Verified: npm --prefix renderer run build produces dist/index.html; GUI npm test 257 pass / 0 fail / 8 skip.
• Agent.md: Batch 5 bullet documents the switch + prestart.
• Vanilla renderer files + vm.runInContext tests deliberately retained for instant revert; cleanup deferred to a follow-up PR (design doc D6).
  CI: run 33006377939 — test 2m0s + test-windows 2m5s, both SUCCESS. Local: pytest 1106 passed + 1 skipped; import + CLI OK. mergeable: MERGEABLE / CLEAN.

[argszero]

✅ LGTM — cycle 2026-08-27T03:49:04

Re-review of head 46edc0a (unchanged since previous vote): full diff confirmed — main.js both loadFile calls → renderer/dist/index.html; gui package.json prestart → npm --prefix renderer run build (fresh-clone npm start safety); Agent.md Batch 5 bullet documents switch + prestart. No issues found; vanilla files retained for revert as designed. CI run 33006377939: test 2m0s + test-windows 2m5s both SUCCESS. LGTM 2/3.

[argszero]

✅ LGTM — cycle 2026-08-27T03:55:17

Third independent review (LGTM 3/3). Head 46edc0a unchanged; full diff re-verified: main.js both loadFile calls → renderer/dist/index.html, gui package.json prestart build hook, Agent.md Batch 5 note. CI run 33006377939 double-green (test + test-windows). mergeable: MERGEABLE / CLEAN. Approving for merge.