Added template API documentation.

Modules-Routes.md

@@ -168,9 +168,11 @@ url = ctx.routes.url_for("/list")
 
 This uses the `public_base_url` from config. If not set, it falls back to `owncast.url`. Set `public_base_url` if Owlbot is hosted on a different domain than your Owncast instance.
 
-## Templates with Jinja2
+## Templates
 
-For HTML pages, [Jinja2](https://jinja.palletsprojects.com/) templates can be used. Jinja2 is already a dependency of Owlbot, so no extra install is needed. Modules that use templates should be structured as a package so the template files can be bundled alongside the code:
+Every module has access to a Jinja2 template environment via `ctx.templates`. Templates are loaded from the module's `templates/` directory first, then from Owlbot's core templates (which includes a Bootstrap `base.html`). Autoescape is enabled by default.
+
+Modules that use templates should be structured as a package so the template files can be bundled alongside the code:
 
 ```
 modules/my_module/
@@ -181,26 +183,36 @@ modules/my_module/
 
 ```python
 # modules/my_module/__init__.py
-from pathlib import Path
-
-import jinja2
 from aiohttp import web
 from owlbot.api import RouteContext, on_route
 
-_template_dir = Path(__file__).resolve().parent / "templates"
-_jinja_env = jinja2.Environment(
-    loader=jinja2.FileSystemLoader(_template_dir),
-    autoescape=True,
-)
-
 @on_route("/list")
 async def list_page(ctx: RouteContext) -> web.Response:
     items = ["apples", "oranges", "bananas"]
-    template = _jinja_env.get_template("list.html")
-    html = template.render(items=items)
+    html = ctx.templates.render("list.html", items=items)
     return web.Response(text=html, content_type="text/html")
 ```
 
+Templates can extend Owlbot's core `base.html` to inherit a Bootstrap layout:
+
+```html
+{# modules/my_module/templates/list.html #}
+{% extends "base.html" %}
+{% block title %}My Items{% endblock %}
+{% block content %}
+<h1>Items</h1>
+<ul>
+    {% for item in items %}
+    <li>{{ item }}</li>
+    {% endfor %}
+</ul>
+{% endblock %}
+```
+
+The `base.html` template provides four blocks: `title`, `head`, `content`, and `scripts`.
+
+For advanced use (custom filters, globals, etc.), access the underlying Jinja2 `Environment` via `ctx.templates.env`.
+
 ## Request Access
 
 `ctx.request` is a standard `aiohttp.web.Request`. Some common patterns:

Modules.md

@@ -248,4 +248,4 @@ async def quotes_page(ctx: RouteContext) -> web.Response:
     )
 ```
 
-For more complex HTML, Jinja2 templates can be used from a package module's `templates/` directory. See [HTTP Routes](Modules-Routes) for that pattern.
+For more complex HTML, use `ctx.templates.render()` with Jinja2 templates from a package module's `templates/` directory. Templates can extend Owlbot's built-in `base.html` for a Bootstrap layout. See [HTTP Routes](Modules-Routes) for details.