Feature request: add image import and camera capture

## Goal Allow users to bring real-world visual content into PenEcho by importing an existing image or taking a photo with the device camera. ## Proposed behavior - Add an **Import image** action that accepts common formats such as PNG, JPEG, and WebP. - Add a **Take photo** action on supported devices and browsers. - Let the user preview, confirm, retake, or cancel a camera capture. - Insert the imported or captured image into the current canvas while preserving its aspect ratio and fitting it within the visible canvas. - Allow the image to be selected, moved, resized, and deleted using the existing canvas interactions. - Include visible imported images in the canvas content sent to the configured AI workflow. ## Permissions and privacy - Request camera permission only after an explicit user action. - Never activate the camera in the background. - Handle unsupported browsers and denied camera permissions with a clear message. - Keep the image local until the user explicitly triggers an AI request. - Avoid retaining unnecessary image metadata. ## Acceptance criteria - A user can import a PNG, JPEG, or WebP image from local storage. - A user can capture a photo on a supported phone, tablet, or computer. - The imported or captured image appears correctly on the canvas without distortion. - Camera denial, cancellation, unsupported devices, and invalid files are handled gracefully. - The feature works with the existing canvas selection and AI request flow. - Automated tests...