Bug: Image input completely broken and ignored in Chat UI due to AST tracker and YAML schema errors on Windows

Before submitting your bug report

• I've tried finding an answer on the Continue docs site
• I'm not able to find an open issue that reports the same bug
• I've seen the troubleshooting guide on the Continue Docs

Relevant environment info

### Describe the bug
The image attachment mechanism is completely broken and non-functional in the Continue chat UI. Absolutely no images or screenshots can be sent. The UI completely ignores `Ctrl + V` pastes and image icon uploads. 

According to the VS Code Developer Tools Console, the extension's background process is stuck in a critical failure state: it fails to register the `config.yaml` schema because the YAML extension is missing, and subsequently drops the configuration file entirely from its internal AST tracker.

### To Reproduce
1. Install Continue extension on Windows.
2. Configure `anthropic/claude-sonnet-4.6` via OpenRouter.
3. Open the chat sidebar and attempt to paste an image or upload it via the icon.
4. The attachment action is completely ignored by the UI, and no image preview appears.

### Expected behavior
The UI should successfully parse the configuration file, register the schema, and allow multimodal image inputs.

### Environment
- **OS:** Windows 10
- **IDE:** VS Code
- **Continue Extension Version:** 1.2.24 / 2.0.0
- **Provider:** OpenRouter
- **Model used:** `anthropic/claude-sonnet-4.6`

### Console Logs (Captured from Toggle Developer Tools)

ERR [Extension Host] Failed to register Continue config.yaml schema, most likely, YAML extension is not installed CodeExpectedError: Unable to write to User Settings because yaml.schemas is not a registered configuration.
    at i5e.toConfigurationEditingError (vscode-file://vscode-app/c:/Users/verst/AppData/Local/Programs/Microsoft%20VS%20Code/fcf604774b/resources/app/out/vs/workbench/workbench.desktop.main.js:5090:7060)
    at i5e.validate (vscode-file://vscode-app/c:/Users/verst/AppData/Local/Programs/Microsoft%20VS%20Code/fcf604774b/resources/app/out/vs/workbench/workbench.desktop.main.js:5090:9830)
    at i5e.doWriteConfiguration (vscode-file://vscode-app/c:/Users/verst/AppData/Local/Programs/Microsoft%20VS%20Code/fcf604774b/resources/app/out/vs/workbench/workbench.desktop.main.js:5090:3453)
    
INFO Auto updating outdated extensions. continue.continue, ritwickdey.liveserver
ERR [Extension Host] Document c:\Users\verst\.continue\config.yaml not found in AST tracker

Description

No response

To reproduce

No response

Log output

Start by reproducing the image paste or upload failure in the Continue chat sidebar on Windows and inspect the extension host logs. Trace registration of the config.yaml schema and the AST tracker error for the missing configuration document. Done means image attachments produce a preview and the schema and AST errors no longer occur.