Add missing hook output fields to match TypeScript SDK (#226)

Closes the gap between Python and TypeScript SDK hook output types by
adding:
- `reason` field for explaining decisions
- `continue_` field for controlling execution flow
- `suppressOutput` field for hiding stdout
- `stopReason` field for stop explanations
- `decision` now supports both "approve" and "block" (not just "block")
- `AsyncHookJSONOutput` type for deferred hook execution
- Proper typing for `hookSpecificOutput` with discriminated unions

Also adds comprehensive examples and tests:
- New examples in hooks.py demonstrating all new fields
- Unit tests in test_tool_callbacks.py for new output types
- E2E tests in e2e-tests/test_hooks.py with real API calls
- CI integration in .github/workflows/test.yml

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude <noreply@anthropic.com>

.github/workflows/test.yml

@@ -125,6 +125,8 @@ jobs:
         run: |
           python examples/quick_start.py
           timeout 120 python examples/streaming_mode.py all
+          timeout 120 python examples/hooks.py PreToolUse
+          timeout 120 python examples/hooks.py DecisionFields
 
       - name: Run example scripts (Windows)
         if: runner.os == 'Windows'
@@ -136,4 +138,14 @@ jobs:
           Wait-Job $job -Timeout 120 | Out-Null
           Stop-Job $job
           Receive-Job $job
+
+          $job = Start-Job { python examples/hooks.py PreToolUse }
+          Wait-Job $job -Timeout 120 | Out-Null
+          Stop-Job $job
+          Receive-Job $job
+
+          $job = Start-Job { python examples/hooks.py DecisionFields }
+          Wait-Job $job -Timeout 120 | Out-Null
+          Stop-Job $job
+          Receive-Job $job
         shell: pwsh