feat(vite): auto-load Jinja2 templates from the Vite provider

[bedus-creation]

Summary

Reimplements the Vite template fix from the reverted PR #133, provider-only — no helper function, no Template class, no ambient/global request, no middleware or ContextVar.

Fresh apps previously got no template engine: ViteProvider.register_jinja_directives() only injected the vite() globals when a templates binding already existed, so a brand-new app had nothing to render with. The provider now binds a Jinja2Templates engine out of the box.

Changes

• ViteConfig: add template: bool = True and templates_directory: str = "resources/templates".
• ViteProvider.register(): when config.template is true and no templates binding exists, build Jinja2Templates(directory=base_path/templates_directory) and bind it. The jinja2/starlette.templating import is guarded and raises a clear install fastapi-startkit[vite] error. An existing templates binding always wins (backward-compatible). register_jinja_directives() is left unchanged.
• Stubs: moved the published template stub to resources/templates/index.html so all published scaffolding is consistent under resources/ (resources/css, resources/js, resources/templates). The stub references {{ vite('resources/js/app.ts') }} and vite.config.ts input resources/js/app.ts — these line up.
• Example: synced example/vite-app/config/vite.py with the new fields. The example keeps binding its own templates engine in FastAPIProvider (registered before ViteProvider), demonstrating the "existing binding wins" path; routes/web.py renders the standard way and is unchanged.

Rendering

Unchanged, standard Starlette/FastAPI:

app.make("templates").TemplateResponse(request, name, context)

No framework rendering helper is introduced.

Explicitly excluded (per task #272)

No vite/template.py, no template() helper, no Template class, no RequestContextMiddleware, no current_request ContextVar, no global/ambient request, and nothing new exported from vite/__init__.py.

Tests

tests/vite/test_template_binding.py covers: binds templates when enabled and none pre-bound; respects an existing binding; skips when template=False; vite()/vite_asset()/vite_react_refresh() present on templates.env.globals after boot; missing-jinja2 raises the clear install error.

• uv run pytest tests/vite/ -v → 36 passed
• uv run pytest --ignore=tests/masoniteorm/postgres --cov → 1553 passed, 7 skipped, total coverage 67.23% (above fail_under)
• ruff format + ruff check clean

Do not merge — merging is the user's job.