feat: Add automatic image format conversion for HEIC/RAW/PSD files

Adds automatic conversion of unsupported image formats (HEIC, HEIF, RAW, PSD)
to JPEG before sending to multimodal-looker agent.

Changes:
- Add image-converter.ts module with format detection and conversion
- Modify look_at tool to auto-convert unsupported formats
- Extend mime-type-inference.ts to support 15+ additional formats
- Use sips (macOS) and ImageMagick (Linux/Windows) for conversion
- Add proper cleanup of temporary files

Fixes #722

Testing:
- All existing tests pass (29/29)
- TypeScript type checking passes
- Verified HEIC to JPEG conversion on macOS

src/tools/look-at/image-converter.ts

@@ -0,0 +1,114 @@
+import { execSync } from "node:child_process"
+import { existsSync, mkdtempSync, unlinkSync } from "node:fs"
+import { tmpdir } from "node:os"
+import { join } from "node:path"
+import { log } from "../../shared"
+
+const SUPPORTED_FORMATS = new Set([
+  "image/jpeg",
+  "image/png",
+  "image/webp",
+  "image/gif",
+  "image/bmp",
+  "image/tiff",
+])
+
+const UNSUPPORTED_FORMATS = new Set([
+  "image/heic",
+  "image/heif",
+  "image/x-canon-cr2",
+  "image/x-canon-crw",
+  "image/x-nikon-nef",
+  "image/x-nikon-nrw",
+  "image/x-sony-arw",
+  "image/x-sony-sr2",
+  "image/x-sony-srf",
+  "image/x-pentax-pef",
+  "image/x-olympus-orf",
+  "image/x-panasonic-raw",
+  "image/x-fuji-raf",
+  "image/x-adobe-dng",
+  "image/vnd.adobe.photoshop",
+  "image/x-photoshop",
+])
+
+export function needsConversion(mimeType: string): boolean {
+  if (SUPPORTED_FORMATS.has(mimeType)) {
+    return false
+  }
+  
+  if (UNSUPPORTED_FORMATS.has(mimeType)) {
+    return true
+  }
+  
+  return mimeType.startsWith("image/")
+}
+
+export function convertImageToJpeg(inputPath: string, mimeType: string): string {
+  if (!existsSync(inputPath)) {
+    throw new Error(`File not found: ${inputPath}`)
+  }
+
+  const tempDir = mkdtempSync(join(tmpdir(), "opencode-img-"))
+  const outputPath = join(tempDir, "converted.jpg")
+
+  log(`[image-converter] Converting ${mimeType} to JPEG: ${inputPath}`)
+
+  try {
+    if (process.platform === "darwin") {
+      try {
+        execSync(`sips -s format jpeg "${inputPath}" --out "${outputPath}"`, {
+          stdio: "pipe",
+          encoding: "utf-8",
+        })
+        
+        if (existsSync(outputPath)) {
+          log(`[image-converter] Converted using sips: ${outputPath}`)
+          return outputPath
+        }
+      } catch (sipsError) {
+        log(`[image-converter] sips failed: ${sipsError}`)
+      }
+    }
+
+    try {
+      execSync(`convert "${inputPath}" "${outputPath}"`, {
+        stdio: "pipe",
+        encoding: "utf-8",
+      })
+      
+      if (existsSync(outputPath)) {
+        log(`[image-converter] Converted using ImageMagick: ${outputPath}`)
+        return outputPath
+      }
+    } catch (convertError) {
+      log(`[image-converter] ImageMagick convert failed: ${convertError}`)
+    }
+
+    throw new Error(
+      `No image conversion tool available. Please install ImageMagick:\n` +
+      `  macOS: brew install imagemagick\n` +
+      `  Ubuntu/Debian: sudo apt install imagemagick\n` +
+      `  RHEL/CentOS: sudo yum install ImageMagick`
+    )
+  } catch (error) {
+    try {
+      if (existsSync(outputPath)) {
+        unlinkSync(outputPath)
+      }
+    } catch {}
+    
+    throw error
+  }
+}
+
+export function cleanupConvertedImage(filePath: string): void {
+  try {
+    if (existsSync(filePath)) {
+      unlinkSync(filePath)
+      log(`[image-converter] Cleaned up temporary file: ${filePath}`)
+    }
+  } catch (error) {
+    log(`[image-converter] Failed to cleanup ${filePath}: ${error}`)
+  }
+}