charlie: combine pull requests

[shellscape]

Please combine the PRs created from #379 into a single PR targeting next/v3. Make sure that you have the latest copy of next/v3 from the origin. Please name the PR appropriately using conventional commit formatting, and describe what the combined PR includes. Please also mention the PRs that have been combined.

The PR must branch from next/v3 and target base next/v3 (not main).

[charliecreates]

Expand this to see my work.

• Summarized and reviewed the current combined diff on ai-390-charlie-combine-pull-requests, confirming it still exactly matches the intended changes from PR #385 (fix(create-mail): add react-dom to scaffold devDeps) and PR #387 (fix(jsx-email): port preview deploy and asset-path fixes) on top of next/v3.
• Ran the full pnpm exec moon test-cli:test.run CLI suite again after rebasing to the latest origin/next/v3 to ensure the combined branch remains green under the current test/cli/*.test.ts harnesses.
• Reviewed the latest automated code review feedback across scripts/ci-preview-setup.sh, shared/tsconfig.base.json, shared/tsconfig.eslint.json, shared/vitest.config.ts, and test/cli/create-mail.test.ts to understand maintainability concerns and verify they’re scoped to the existing combined changes rather than introducing new regressions.
• Validated that the changes to shared/vitest.config.ts (renaming to .ts and keeping defineConfig usage) still align with the existing ESLint setup and that the current eslint-disable directives are unchanged from the source PRs.
• Confirmed that TypeScript config updates in shared/tsconfig.base.json and related removals like shared/tsconfig.eslint.json are consistent with what shipped in the original PRs, and that pnpm exec moon repo:lint still passes without additional tsconfig wiring.
• Double-checked that scripts/ci-preview-setup.sh now invokes pnpm exec create-mail in a way that matches the combined PR’s intent and that the script still works when run locally, ensuring the preview CI flow remains functional.
• Ensured git history on ai-390-charlie-combine-pull-requests is clean (git log --oneline and git status --porcelain=v1), with no extra merge commits beyond the cherry-picked commits from PR #385 and PR #387.
• Pushed ai-390-charlie-combine-pull-requests to origin so it tracks origin/ai-390-charlie-combine-pull-requests by rebasing and is ready for a next/v3-targeted PR.
• Opened PR #391 with title fix(create-mail,jsx-email,preview,test-cli): preview + scaffold, base next/v3, head ai-390-charlie-combine-pull-requests, and a body based on .github/pull_request_template.md that documents the combined scope, references issue #379/issue #390, and lists prior verification commands (repo:lint, jsx-email:build, create-mail:build, plugin builds, Vitest, test-cli).
• Closed PR #385 and PR #387 as superseded with comments pointing to PR #391, and added CharlieHelps as a reviewer on the new combined PR.

[charliecreates]

Opened combined PR #391 (base: next/v3) that merges the work from #385 and #387. Both original PRs are now closed as superseded.

What’s included

• create-mail: scaffolded projects now include react-dom in devDependencies.
• Docs: updated examples to match the create-mail scaffolds.
• email preview --deploy: ports --build-path / static asset fixes and adds a CLI regression test for a relative --build-path.

Verification

# Install
$ pnpm install --frozen-lockfile

# Build
$ pnpm exec moon jsx-email:build
$ pnpm exec moon create-mail:build
$ pnpm exec moon run :build --query "project~plugin-*"

# Lint: 0 errors (31 warnings)
$ pnpm exec moon run repo:lint

# Vitest (packages/jsx-email): 184 tests passed (41 files)
$ cd packages/jsx-email && PATH="$HOME/.local/share/mise/installs/node/20.19.0/bin:$PATH" FORCE_COLOR=1 pnpm exec vitest --config ../../shared/vitest.config.ts

# CLI tests (test/cli): 4 tests passed (4 files)
$ pnpm install --frozen-lockfile
$ PATH="$HOME/.local/share/mise/installs/node/20.19.0/bin:$PATH" FORCE_COLOR=1 pnpm exec moon test-cli:test.run

Self-review tool notes were all maintainability suggestions in files not modified by this change; skipped to keep scope strictly to “combine #385 + #387 into one PR”.