Have read_file support images (#30435)

This is very basic support for them. There are a number of other TODOs
before this is really a first-class supported feature, so not adding any
release notes for it; for now, this PR just makes it so that if
read_file tries to read a PNG (which has come up in practice), it at
least correctly sends it to Anthropic instead of messing up.

This also lays the groundwork for future PRs for more first-class
support for images in tool calls across more image file formats and LLM
providers.

Release Notes:

- N/A

---------

Co-authored-by: Agus Zubiaga <hi@aguz.me>
Co-authored-by: Agus Zubiaga <agus@zed.dev>

crates/language_models/src/provider/ollama.rs

@@ -325,6 +325,10 @@ impl LanguageModel for OllamaLanguageModel {
         self.model.supports_tools.unwrap_or(false)
     }
 
+    fn supports_images(&self) -> bool {
+        false
+    }
+
     fn supports_tool_choice(&self, choice: LanguageModelToolChoice) -> bool {
         match choice {
             LanguageModelToolChoice::Auto => false,