docs: load media examples from disk instead of inline base64 (#3108)

docs/servers/media.md

@@ -6,17 +6,17 @@ The SDK ships two helpers for binary results (**`Image`** and **`Audio`**) and a
 
 ## Returning an image
 
-Annotate the return type as `Image` and return one:
+Annotate the return type as `Image`, point it at a file, and return it:
 
-```python title="server.py" hl_lines="14 16"
+```python title="server.py" hl_lines="8 12 14"
 --8<-- "docs_src/media/tutorial001.py"
 ```
 
-* `Image` takes exactly one of `data` (raw bytes) or `path` (a file to read).
-* `format="png"` becomes the MIME type the client sees: `image/png`.
-* The bytes here are a one-pixel placeholder so the file runs on its own. In a real server they come from Pillow, matplotlib, a headless browser, or anything else that hands you `bytes`.
+* `Image` takes exactly one of `path` (a file to read) or `data` (raw bytes).
+* The MIME type the client sees is guessed from the suffix: `logo.png` is announced as `image/png`.
+* Nothing here is special about logos. Any PNG next to `server.py` works: a chart your code rendered, a diagram, a photo.
 
-`Image` is an SDK convenience, not a protocol type. On the wire your return value becomes an **`ImageContent`** block (your bytes base64-encoded, plus the MIME type):
+`Image` is an SDK convenience, not a protocol type. On the wire your return value becomes an **`ImageContent`** block (the file's bytes base64-encoded, plus the MIME type):
 
 ```python
 result.content             # [ImageContent(type="image", data="iVBORw0KGgoAAAANSUhEUg...", mime_type="image/png")]
@@ -25,7 +25,7 @@ result.structured_content  # None
 
 Two things to notice:
 
-* `data` is base64. You returned raw `bytes`; the SDK did the encoding.
+* `data` is base64. You never touched the bytes; the SDK read the file and did the encoding.
 * `structured_content` is `None`. An `Image` is content for the model to look at, not data for the application to parse: there is no output schema. (Contrast **[Structured Output](structured-output.md)**, where the return annotation *is* the schema.)
 
 !!! info
@@ -35,32 +35,40 @@ Two things to notice:
 
 ### Try it
 
+Drop any PNG next to `server.py`, name it `logo.png`, and run:
+
 ```console
 uv run mcp dev server.py
 ```
 
-Open the **Tools** tab and call `logo`. The result is not a string: it is an `image` content block, and the Inspector renders it as a picture. You returned `bytes`; everything between that and the pixels on screen was the SDK.
+Open the **Tools** tab and call `logo`. The result is not a string: it is an `image` content block, and the Inspector renders your picture. Everything between the file on disk and the pixels on screen was the SDK.
 
 ## Returning audio
 
-`Audio` is the same shape:
+`Audio` is the same shape. Keep `logo.png` where it was, and put any WAV beside it as `chime.wav`:
 
-```python title="server.py" hl_lines="21-24"
+```python title="server.py" hl_lines="18-21"
 --8<-- "docs_src/media/tutorial002.py"
 ```
 
 The result is an **`AudioContent`** block:
 
 ```python
-result.content             # [AudioContent(type="audio", data="UklGRjQAAABXQVZFZm1...", mime_type="audio/wav")]
+result.content             # [AudioContent(type="audio", data="UklGR...", mime_type="audio/wav")]
 result.structured_content  # None
 ```
 
-Same deal: raw bytes in, base64 and a MIME type out, no output schema.
+Same deal: a file on disk in, base64 and a MIME type out, no output schema.
 
 ## Bytes or a file
 
-Both helpers also accept `path=` instead of `data=`. The file is read when the result is built, and the MIME type is guessed from the suffix:
+Both helpers also accept `data=` (raw bytes) instead of `path=`. That is the mode for bytes that never came from a file of their own — a database column, an HTTP response, something Pillow just drew:
+
+```python title="server.py" hl_lines="14 15"
+--8<-- "docs_src/media/tutorial003.py"
+```
+
+With `path=` there is nothing to declare: the file is read when the result is built, and the MIME type is guessed from the suffix:
 
 * `Image`: `.png`, `.jpg`, `.jpeg`, `.gif`, `.webp`.
 * `Audio`: `.wav`, `.mp3`, `.ogg`, `.flac`, `.aac`, `.m4a`.
@@ -78,7 +86,7 @@ A suffix it doesn't recognise falls back to `application/octet-stream`.
 An `Icon` is metadata, not content. It doesn't carry the image; it points at one with a URI, and a client may fetch it and show it next to your server's name, a tool, a resource, or a prompt.
 
 ```python title="server.py" hl_lines="5-6 8 11 17"
---8<-- "docs_src/media/tutorial003.py"
+--8<-- "docs_src/media/tutorial004.py"
 ```
 
 * `src` is a URI the client can resolve: `https:`, or a `data:` URI if you want the icon embedded with no extra fetch.
@@ -100,7 +108,7 @@ A tool's icons are on the `Tool` object from `tools/list`, a resource's on the `
 ## Recap
 
 * Return an `Image` or `Audio` from a tool and the client receives an `ImageContent` / `AudioContent` block: your bytes base64-encoded, with a MIME type.
-* Build one from in-memory `data=` plus an explicit `format=`, or from a `path=` and let the suffix decide.
+* Build one from a `path=` and let the suffix decide the MIME type, or from in-memory `data=` plus an explicit `format=`.
 * Media results carry no `structured_content` and no output schema.
 * An `Icon` is a pointer: a `src` URI plus optional `mime_type`, `sizes`, and `theme`.
 * `icons=[...]` works on the server, on tools, on resources, and on prompts, and clients find them on the matching objects.