fix(reload): close the NotifyReload connection after the POST (#1)

An idle pooled keep-alive connection to the Vite (Node) dev server is
torn down by Node's keepAliveTimeout, and the teardown can emit an
unsolicited "HTTP/1.1 400 Bad Request" that Go's transport logs as

    Unsolicited response received on idle HTTP channel starting with
    "HTTP/1.1 400 Bad Request\r\n\r\n"; err=<nil>

in the app's terminal output — alarming noise, nothing actually wrong.
NotifyReload makes exactly one POST per server start, so close the
connection instead of pooling it.

Claude-Session: https://claude.ai/code/session_01QA44dyPcgxnjeJJDhcEKak

fix(manifest): resolve a CSS-only entry to CSS, not JS

A standalone CSS entry (e.g. a Tailwind stylesheet built as its own Vite entry,
manifest file ending in .css) was placed in Bundle.JS, so callers rendered it as
a <script type="module">. In prod the browser rejects a .css module script on
MIME type ("Expected a JavaScript module but got text/css"); in dev the Vite
server serves it as JS so it slipped through. Route a .css entry file to
Bundle.CSS so it renders as <link rel="stylesheet">.

Config.Entries: friendly-name → source-path resolution in Entry

feat: context helpers — NewContext/FromContext/Middleware (v0.2.0)

Stash/retrieve *Vite via context.Context so handlers and templates read the
asset bundle from ctx instead of threading it as a parameter. Unexported
context key (no collision), nil-safe FromContext, request-scoped Middleware.

Claude-Session: https://claude.ai/code/session_01WYfSGNoFisL8JdENKfL5CA

fix: drop redundant go before NotifyReload in README; check err + add…

… StaticURL test (final-review fixes)