add lambda logo, fold sections, add python/error/log snippets

- Pull the rethink lambda logo (assets/img/logo.svg) into docs/assets and
  wire it as theme.logo + favicon — matches the Gitea brand mark.
- standards.md: fold six thin sections into three fuller ones (Files and
  style / Documentation / Quality and error handling), each illustrated
  with python snippets, a flake8 output block, Do/Don't tabbed examples,
  a traceback, and a log line. Admonitions for the run-it-locally tip and
  the lib-logging note.
- libraries.md: add a collapsible 'using a library' example (pyproject
  pin + import/usage python snippet).

Verified in-browser: logo renders in the header, snippets/tabs/traceback/
log blocks render against the dark theme, libraries example expands.
mkdocs build --strict clean.

Signed-off-by: disqualifier <dev@disqualifier.me>

docs/libraries.md

@@ -11,10 +11,44 @@ the repo, where the README and tags live.
 
 ## Install
 
+Pin a tag in your dependencies — never an unpinned branch:
+
 ```
 <lib> @ git+https://git.rethinkstudios.io/rethink-public/<lib>.git@<tag>
 ```
 
+??? example "Using a library — install, import, go"
+
+    Add it to your project's deps (e.g. `pyproject.toml`):
+
+    ```toml
+    [project]
+    dependencies = [
+        "aioweb @ git+https://git.rethinkstudios.io/rethink-public/aioweb.git@v0.3.1",
+    ]
+    ```
+
+    Then use it — the README in each repo has the real surface; this is the shape:
+
+    ```python
+    import asyncio
+
+    from aioweb import Session
+
+
+    async def main() -> None:
+        """fetch a page through the shared async http session"""
+        async with Session() as web:
+            resp = await web.get("https://example.test")
+            print(resp.status, len(resp.content))
+
+
+    asyncio.run(main())
+    ```
+
+    Need to bump a lib? Change the `@<tag>` and reinstall — versions live with the
+    lib, not in these docs.
+
 <div id="lib-list" markdown="0">
   <p class="lib-status">Loading libraries from Gitea…</p>
 </div>