Add component props and lambda event handlers (TDD)

Implements two major features using Test-Driven Development:

1. Component Props/Parameters:
   - Components can accept parameters: @component def Button(label)
   - Arguments passed when yielding: yield Button("Click me")
   - Default values supported: def Tabs(orientation=0)
   - Codegen passes arguments correctly to render functions

2. Lambda Event Handlers:
   - Support onclick=lambda: function_call() syntax
   - Parser converts lambdas to synthetic functions
   - Synthetic functions auto-named: _lambda_0_ComponentName
   - Codegen emits lambda functions as event handlers
   - Clean syntax vs set_tab_0/1/2 boilerplate

Implementation:
   - Added _process_lambdas_in_component() to scan & convert
   - Lambda detection in _transform_expr()
   - "expr" statement type for lambda bodies
   - Component argument passing in _emit_yield_component()
   - Constants vs variables handled correctly in args

Tests (TDD Style):
   - test_component_props.py (8 tests) - all passing
   - test_lambda_simple.py (3 tests) - all passing
   - 46 total tests passing

Examples:
   # Before (verbose)
   def set_tab_0(): tab = 0
   def set_tab_1(): tab = 1
   with Button(onclick=set_tab_0): yield "Tab 0"

   # After (clean)
   with Button(onclick=lambda: set_tab(0)): yield "Tab 0"
   with Button(onclick=lambda: set_tab(1)): yield "Tab 1"

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

Co-Authored-By: Claude <noreply@anthropic.com>

tests/test_lambda_simple.py

@@ -0,0 +1,87 @@
+"""Tests for simple lambda support - starting with valid Python syntax."""
+
+import pytest
+from ritz.parser import parse_component
+from ritz.llvm_codegen_signals import generate_llvm_ir
+
+
+def test_parse_lambda_calling_function():
+    """Test lambda that calls a function - valid Python syntax."""
+    source = """
+from ritz.syntax import *
+
+@component
+def App():
+    count = signal(0)
+
+    def increment():
+        count += 1
+
+    with Button(onclick=lambda: increment()):
+        yield "Click"
+"""
+    ir = parse_component(source)
+
+    # Parser should recognize lambda in onclick and convert to synthetic function
+    with_stmt = [s for s in ir["body"] if s["type"] == "with"][0]
+    assert "onclick" in with_stmt["element"]["props"]
+    # After lambda processing, onclick should reference a synthetic function
+    onclick_ref = with_stmt["element"]["props"]["onclick"]
+    assert onclick_ref["type"] == "name"
+    assert onclick_ref["id"].startswith("_lambda_")
+
+
+def test_codegen_lambda_calling_function():
+    """Test LLVM codegen for lambda calling a function."""
+    source = """
+from ritz.syntax import *
+
+@component
+def App():
+    count = signal(0)
+
+    def increment():
+        count += 1
+
+    with Button(onclick=lambda: increment()):
+        yield "+"
+"""
+    ir = parse_component(source)
+    llvm_ir = generate_llvm_ir(ir)
+
+    # Should generate a lambda handler that calls increment
+    assert "define void @_lambda_0_App()" in llvm_ir
+    assert "call void @increment()" in llvm_ir
+    assert "js_bind_event" in llvm_ir
+
+
+def test_lambda_inline_for_simple_setter():
+    """Test using lambda for simple signal setter calls."""
+    source = """
+from ritz.syntax import *
+
+@component
+def Tabs():
+    tab = signal(0)
+
+    def set_tab(value):
+        tab = value
+
+    with Button(onclick=lambda: set_tab(0)):
+        yield "Tab 0"
+
+    with Button(onclick=lambda: set_tab(1)):
+        yield "Tab 1"
+"""
+    ir = parse_component(source)
+
+    # Should have two with statements with lambda onclick handlers (converted to functions)
+    with_stmts = [s for s in ir["body"] if s["type"] == "with"]
+    assert len([w for w in with_stmts if "onclick" in w["element"]["props"]]) == 2
+
+    # Check that both have synthetic lambda functions
+    for with_stmt in with_stmts:
+        if "onclick" in with_stmt["element"]["props"]:
+            onclick_ref = with_stmt["element"]["props"]["onclick"]
+            assert onclick_ref["type"] == "name"
+            assert onclick_ref["id"].startswith("_lambda_")