Add Liquid to Ruby compiler for optimized template rendering

This adds a new `compile_to_ruby` method to Liquid::Template that compiles
Liquid templates to pure Ruby code. The compiled code can be eval'd to create
a proc that renders templates without needing the Liquid library at runtime.

## Features

- Compiles all standard Liquid tags: if/unless/case, for, assign, capture,
  cycle, increment/decrement, raw, echo, break/continue, comment, tablerow
- Compiles variable expressions with filter chains to direct Ruby method calls
- Supports static partial inlining ({% render %} and {% include %} with string
  literals are loaded and compiled at compile time)
- Dynamic partial support via runtime callbacks (__render_dynamic__, __include_dynamic__)
- Debug mode with source comments for error tracing (lightweight source map)
- SourceMapper utility to trace runtime errors back to Liquid source

## Optimization Opportunities

The compiled Ruby code has significant performance advantages:

1. No Context object - variables accessed directly from assigns hash
2. No filter invocation overhead - direct Ruby method calls
3. No resource limits tracking - no per-node render score updates
4. No stack-based scoping - uses Ruby's native block scoping
5. Direct string concatenation - no render_to_output_buffer abstraction
6. Native control flow - break/continue use Ruby's throw/catch
7. No to_liquid calls - values used directly
8. No profiling hooks - no profiler overhead
9. No exception rendering - errors propagate naturally

## Usage

```ruby
template = Liquid::Template.parse("Hello, {{ name }}!")
ruby_code = template.compile_to_ruby
render_proc = eval(ruby_code)
result = render_proc.call({ "name" => "World" })
# => "Hello, World!"

# With debug mode for error tracing:
ruby_code = template.compile_to_ruby(debug: true)
```

## Limitations

- Dynamic {% render %} and {% include %} require runtime callback methods
- Custom tags need explicit compiler implementations
- Custom filters must be available at runtime

lib/liquid/compile/condition_compiler.rb

@@ -0,0 +1,125 @@
+# frozen_string_literal: true
+
+module Liquid
+  module Compile
+    # ConditionCompiler compiles Liquid conditions to Ruby boolean expressions.
+    #
+    # Handles:
+    # - Simple truthiness: {% if variable %}
+    # - Comparisons: {% if a == b %}, {% if a > b %}
+    # - Logical operators: {% if a and b %}, {% if a or b %}
+    # - Special checks: {% if a == blank %}, {% if a == empty %}
+    class ConditionCompiler
+      # Operator mappings from Liquid to Ruby
+      OPERATORS = {
+        '==' => '==',
+        '!=' => '!=',
+        '<>' => '!=',
+        '<' => '<',
+        '>' => '>',
+        '<=' => '<=',
+        '>=' => '>=',
+        'contains' => :contains,
+      }.freeze
+
+      # Compile a Condition to a Ruby boolean expression
+      # @param condition [Liquid::Condition] The condition
+      # @param compiler [RubyCompiler] The main compiler instance
+      # @return [String] Ruby code expression that evaluates to true/false
+      def self.compile(condition, compiler)
+        if condition.is_a?(ElseCondition)
+          return "true"
+        end
+
+        compile_condition_chain(condition, compiler)
+      end
+
+      private
+
+      def self.compile_condition_chain(condition, compiler)
+        # Compile the current condition
+        current = compile_single_condition(condition, compiler)
+
+        # Check for chained conditions (and/or)
+        if condition.child_condition
+          child = compile_condition_chain(condition.child_condition, compiler)
+          child_relation = condition.send(:child_relation)
+
+          case child_relation
+          when :and
+            "(#{current} && #{child})"
+          when :or
+            "(#{current} || #{child})"
+          else
+            current
+          end
+        else
+          current
+        end
+      end
+
+      def self.compile_single_condition(condition, compiler)
+        left = condition.left
+        op = condition.operator
+        right = condition.right
+
+        # If no operator, just check truthiness
+        if op.nil?
+          left_expr = ExpressionCompiler.compile(left, compiler)
+          return "__truthy__(#{left_expr})"
+        end
+
+        # Compile left and right expressions
+        left_expr = compile_condition_value(left, compiler)
+        right_expr = compile_condition_value(right, compiler)
+
+        # Handle special operators
+        case OPERATORS[op]
+        when :contains
+          compile_contains(left_expr, right_expr, compiler)
+        when '=='
+          compile_equality(left, right, left_expr, right_expr, compiler)
+        when '!='
+          "!(#{compile_equality(left, right, left_expr, right_expr, compiler)})"
+        else
+          # Standard comparison
+          ruby_op = OPERATORS[op] || op
+          "(#{left_expr} #{ruby_op} #{right_expr} rescue false)"
+        end
+      end
+
+      def self.compile_condition_value(expr, compiler)
+        if expr.is_a?(Condition::MethodLiteral)
+          # For blank/empty checks, we return a special marker
+          # The equality handler will deal with this
+          ":__method_literal_#{expr.method_name}__"
+        else
+          ExpressionCompiler.compile(expr, compiler)
+        end
+      end
+
+      def self.compile_equality(left, right, left_expr, right_expr, compiler)
+        # Handle blank/empty method literals
+        if left.is_a?(Condition::MethodLiteral)
+          method_name = left.method_name
+          "(#{right_expr}.respond_to?(:#{method_name}) ? #{right_expr}.#{method_name} : nil)"
+        elsif right.is_a?(Condition::MethodLiteral)
+          method_name = right.method_name
+          "(#{left_expr}.respond_to?(:#{method_name}) ? #{left_expr}.#{method_name} : nil)"
+        else
+          "(#{left_expr} == #{right_expr})"
+        end
+      end
+
+      def self.compile_contains(left_expr, right_expr, compiler)
+        # The contains operator checks if left includes right
+        # For strings, right is converted to a string
+        "(lambda { |left, right| " \
+          "return false if left.nil? || right.nil? || !left.respond_to?(:include?); " \
+          "right = right.to_s if left.is_a?(String); " \
+          "left.include?(right) rescue false " \
+          "}.call(#{left_expr}, #{right_expr}))"
+      end
+    end
+  end
+end