refactor: complete v1.0 simplification by removing all legacy inputs

- Remove all backward compatibility for v1.0 simplification
- Remove 10 legacy inputs from base-action/action.yml
- Remove 9 legacy inputs from main action.yml
- Simplify ClaudeOptions type to just timeoutMinutes and claudeArgs
- Remove all legacy option handling from prepareRunConfig
- Update tests to remove references to deleted fields
- Remove obsolete test file github/context.test.ts
- Clean up types to remove customInstructions, allowedTools, disallowedTools

Users now use claudeArgs exclusively for CLI control.

examples/claude-experimental-review-mode.yml

@@ -27,13 +27,14 @@ jobs:
           fetch-depth: 0 # Full history for better diff analysis
 
       - name: Code Review with Claude
-        uses: anthropics/claude-code-action@beta
+        uses: anthropics/claude-code-action@v1
         with:
-          mode: experimental-review
           anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
           # github_token not needed - uses default GITHUB_TOKEN for GitHub operations
           timeout_minutes: "30"
-          custom_instructions: |
+          prompt: |
+            Review this pull request comprehensively.
+
             Focus on:
             - Code quality and maintainability
             - Security vulnerabilities