refactor(hooks): deprecate block-image-read, add CLIProxy fallback

- Remove redundant block-image-read.cjs hook (image-analyzer handles all)
- Add fallback blocking when CLIProxy unavailable (prevents context overflow)
- Simplify fallback message to prevent context pollution/hallucination
- Remove image-read-block-hook-env.ts and related exports
- Update comments per PR #442 review suggestions
- Add defensive check for empty models array

Closes #426

src/utils/shell-executor.ts

@@ -7,7 +7,6 @@
 import { spawn, ChildProcess } from 'child_process';
 import { ErrorManager } from './error-manager';
 import { getWebSearchHookEnv } from './websearch-manager';
-import { getImageReadBlockHookEnv } from './hooks/image-read-block-hook-env';
 
 /**
  * Escape arguments for shell execution (Windows compatibility)
@@ -53,12 +52,11 @@ export function execClaude(
 
   // Get WebSearch hook config env vars
   const webSearchEnv = getWebSearchHookEnv();
-  const imageReadBlockEnv = getImageReadBlockHookEnv();
 
   // Prepare environment (merge with process.env if envVars provided)
   const env = envVars
-    ? { ...process.env, ...envVars, ...webSearchEnv, ...imageReadBlockEnv }
-    : { ...process.env, ...webSearchEnv, ...imageReadBlockEnv };
+    ? { ...process.env, ...envVars, ...webSearchEnv }
+    : { ...process.env, ...webSearchEnv };
 
   let child: ChildProcess;
   if (needsShell) {