Add typed text pages; serve CSS as compiled-on-demand /css/main.css

Sidecar-less page bundles whose directory ends in a MediaType extension
(.txt/.css/.xml/.json/.js) now render raw (no HTML layout, autoescape off),
are served with that extension's Content-Type, and cache as a flat file
(public/cache/<path>) so Apache serves them directly via a new .htaccess
rule. They're excluded from the content index.

CSS becomes one of these: novaconium/pages/css/main.css/ holds index.twig
({{ sass('main.sass') }}), main.sass, and _colors.sass. App\SassExtension's
sass() Twig function resolves the entry file through the overlay and shells
out to Dart Sass on a cache miss; Lib\SassCompiler wraps the CLI. This
drops the committed App/css/main.css build artifact and the public/css
bind mount. Override styling by copying the whole bundle to App/pages/.

Also ship robots.txt and humans.txt as framework bundles, and drop the
php -S dev router (public/router.php) - Docker/Apache only now.

New: novaconium/src/MediaType.php, SassExtension.php, lib/SassCompiler.php.
Moved: novaconium/sass/ -> novaconium/pages/css/main.css/ (+ App/sass merged).
Docs: AGENTS.md, new /admin/docs/text-pages, and styling/caching/docker/
design-notes/getting-started/project-layout/config docs updated.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018Q9cAXC9xcXYnmP7qjsnw7

AGENTS.md

@@ -50,18 +50,19 @@ vendored as plain source files.
 ## The two-root split
 
 - **`App/`** — the project: `App/pages/`, `App/lib/` (`Lib\` classes),
-  `App/config.php`, `App/migrations/`, `App/sass/`. The only directory a
-  site author is expected to touch.
+  `App/config.php`, `App/migrations/`. The only directory a site author is
+  expected to touch.
 - **`novaconium/`** — the framework: router/renderer core
-  (`novaconium/src/`), default pages/libs, vendored Twig, autoloader,
-  config, bootstrap.
+  (`novaconium/src/`), default pages/libs (including the `css/main.css/`,
+  `robots.txt/`, `humans.txt/` bundles), vendored Twig, autoloader, config,
+  bootstrap.
 
 Routing/rendering resolve against **both roots, `App/` first** (via
 `novaconium/src/Overlay.php` for pages, `novaconium/autoload.php` for
 `Lib\` classes) — same override-by-presence mechanism used for
-`config.php`, Twig's `FilesystemLoader`, and Sass (see below). A project
-only lists the config keys it's changing in `App/config.php`; never edit
-`novaconium/config.php` directly.
+`config.php` and Twig's `FilesystemLoader`. A project only lists the config
+keys it's changing in `App/config.php`; never edit `novaconium/config.php`
+directly.
 
 **`db_connections` is the one config key that isn't a plain shallow-merge.**
 `Lib\Db::config()` (and the duplicate in `bin/migrate.php`) merges it one
@@ -139,19 +140,39 @@ syntax (`{% %}`/`{{ }}`) — highlight.js has no Twig grammar and a
 restricted auto-detect still always guesses wrong without this class. Any
 new Twig-syntax code sample needs it; PHP/Bash samples don't.
 
-## Sass override quirk
+## Typed text pages (CSS, robots.txt, humans.txt, …)
 
-`novaconium/sass/main.sass` does `@use 'colors' as *` with **no**
-`_colors.sass` sibling in `novaconium/sass/` — on purpose. Dart Sass
-resolves a bare `@use` relative to the importing file's own directory
-*before* `--load-path`, so a sibling file would always win and silently
-defeat the `App/sass/_colors.sass` override. The framework default lives
-at `novaconium/sass/defaults/_colors.sass` instead. Don't move it back.
+A sidecar-less page bundle whose **directory segment ends in an extension**
+in `App\MediaType::MAP` (`.txt` `.css` `.xml` `.json` `.js`) is a *typed
+text page*: `Renderer` renders its `index.twig` with **no** HTML layout and
+**autoescaping off**, serves it with that extension's Content-Type, and
+`Cache` writes it as a flat file (`public/cache/css/main.css`, not
+`.../index.html`). A rewrite in `public/.htaccess` (rule 2b) then serves
+that file straight from Apache on every later request — so the extension
+list is duplicated there; keep it in sync with `MediaType::MAP`. These
+pages are excluded from the content index (`ContentIndexer::isCrawlable()`).
+See `/admin/docs/text-pages`.
 
-Every color rule in `main.sass` reads a CSS custom property (`var(--bg)`,
-etc.), never a Sass variable directly — required for the runtime dark/light
-toggle. Adding a color means adding both the plain and `-light` variable in
-**both** `_colors.sass` files and wiring it into both `:root` blocks.
+The framework ships three: `novaconium/pages/css/main.css/` (route
+`/css/main.css`), `novaconium/pages/robots.txt/`, `novaconium/pages/humans.txt/`.
+A project overrides one the normal App-over-novaconium way — put its own
+bundle at the same relative path under `App/pages/`.
+
+CSS is the interesting one: `novaconium/pages/css/main.css/` holds
+`index.twig` (`{{- sass('main.sass') -}}`), `main.sass`, and `_colors.sass`.
+The `sass()` Twig function (`App\SassExtension` → `Lib\SassCompiler`)
+resolves the entry file through the overlay (App first) and shells out to
+Dart Sass with that file's own directory as the sole `--load-path`, so
+`@use 'colors'` resolves to the sibling `_colors.sass` in whichever copy of
+the bundle won. To customise styling, copy the **whole** `css/main.css/`
+bundle to `App/pages/css/main.css/` — there's no partial "just
+`_colors.sass`" override.
+Output is cached like any typed page; run
+`php novaconium/bin/clear-cache.php` after editing Sass. Every color rule
+reads a CSS custom property (`var(--bg)` …), never a Sass variable directly
+— required for the runtime dark/light toggle; adding a color means adding
+its plain and `-light` variable in `_colors.sass` and wiring both into the
+two `:root` blocks in `main.sass`.
 
 ## Input handling
 
@@ -166,12 +187,14 @@ to be hashed) read `$_POST` directly — see login/users sidecars.
 
 ## Running it
 
+Only via the Docker image built from `Dockerfile` (Apache reads
+`public/.htaccess` directly — there is no `php -S` dev router). Typically:
+
 ```
-php -S 127.0.0.1:8000 -t public public/router.php
+docker compose up   # image + volumes from docker-compose.yml
 ```
 
-`public/router.php` is dev-only, mimics `public/.htaccess`. There is no
-test suite — verification is manual route-by-route (see
+There is no test suite — verification is manual route-by-route (see
 `/admin/docs/design-notes`'s Verification section). After testing, clear
 stray cache with `php novaconium/bin/clear-cache.php` and remove any
 test-only debris from `App/lib/`/`App/pages/` — nothing there is gitignored
@@ -190,13 +213,11 @@ except `public/cache/*` and `novaconium/contact-log.txt`.
 - `novaconium/bin/` holds standalone CLI entry points
   (`php novaconium/bin/<script>.php`) — distinct from
   `bootstrap.php`/`autoload.php`/`config.php`, which are only `require`'d.
-- CSS compiles from `novaconium/sass/main.sass` (indented syntax) to
-  `App/css/main.css` (project-owned; docker-compose mounts `App/css` to
-  the container's `public/css`, and it's served at `/css/main.css`):
-  `sass --load-path=App/sass --load-path=novaconium/sass/defaults --no-source-map novaconium/sass/main.sass App/css/main.css`
-  — commit the regenerated CSS. The Docker image ships Dart Sass standalone
-  (pinned `DART_SASS_VERSION` in the `Dockerfile`, symlinked to
-  `/usr/local/bin/sass`), so the same command runs inside the container;
-  bump that version deliberately, like the PHP base tag. See
-  `/admin/docs/styling` for the Docker fallback if `sass` isn't installed
-  locally.
+- CSS is a **typed text page** (see that section above), not a build
+  artifact: the Sass lives in `novaconium/pages/css/main.css/` (override at
+  `App/pages/css/main.css/`) and is compiled on demand by the `sass()` Twig
+  function, cached to `public/cache/css/main.css`. There is nothing to
+  pre-build or commit. The Docker image ships Dart Sass standalone (pinned
+  `DART_SASS_VERSION` in the `Dockerfile`, symlinked to
+  `/usr/local/bin/sass`) as a runtime dependency. See `/admin/docs/styling`
+  and `/admin/docs/text-pages`.