test: add integration fixtures for builtin method type resolution

Add dict_method_types and list_method_types test fixtures that exercise
the full compilation pipeline for registry-based member access resolution
(items/keys/values/get for dict; append/insert/pop/remove/count/sort/
reverse/copy/clear for list).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: antonsynd

src/Sharpy.Compiler.Tests/Integration/TestFixtures/collections/dict_method_types.expected

@@ -0,0 +1,12 @@
+x
+10
+y
+20
+z
+30
+3
+60
+10
+-1
+20
+0

src/Sharpy.Compiler.Tests/Integration/TestFixtures/collections/dict_method_types.spy

@@ -0,0 +1,31 @@
+# Test: dict method type resolution through BuiltinMethodDefinitions
+# Exercises items(), keys(), values(), get() via the registry-based member access path
+def main():
+    d: dict[str, int] = {"x": 10, "y": 20, "z": 30}
+
+    # items() - iterates key-value pairs
+    for k, v in d.items():
+        print(k)
+        print(v)
+
+    # keys() - iterates keys
+    key_count: int = 0
+    for k in d.keys():
+        key_count += 1
+    print(key_count)
+
+    # values() - iterates values
+    total: int = 0
+    for v in d.values():
+        total += v
+    print(total)
+
+    # get(key, default) - 2-arg form returns V
+    val: int = d.get("x", 0)
+    print(val)
+    print(d.get("missing", -1))
+
+    # get(key) - 1-arg form returns V? (Optional)
+    result = d.get("y")
+    print(result)
+    print(d.get("nope"))

src/Sharpy.Compiler.Tests/Integration/TestFixtures/collections/list_method_types.expected

@@ -0,0 +1,17 @@
+4
+4
+0
+5
+4
+4
+0
+4
+3
+2
+1
+2
+2
+3
+4
+0
+4

src/Sharpy.Compiler.Tests/Integration/TestFixtures/collections/list_method_types.spy

@@ -0,0 +1,52 @@
+# Test: list method type resolution through BuiltinMethodDefinitions
+# Exercises append, insert, pop, remove, count, sort, reverse, copy, clear
+def main():
+    nums: list[int] = [3, 1, 2]
+
+    # append - returns void, mutates list
+    nums.append(4)
+    print(len(nums))
+    print(nums[3])
+
+    # insert - returns void, inserts at index
+    nums.insert(0, 0)
+    print(nums[0])
+    print(len(nums))
+
+    # pop() - no args, returns T
+    last: int = nums.pop()
+    print(last)
+    print(len(nums))
+
+    # pop(index) - returns T
+    first: int = nums.pop(0)
+    print(first)
+
+    # remove - removes first occurrence
+    nums.append(1)
+    print(len(nums))
+    nums.remove(1)
+    print(len(nums))
+
+    # count
+    nums.append(2)
+    print(nums.count(2))
+
+    # sort
+    nums.sort()
+    print(nums[0])
+    print(nums[1])
+    print(nums[2])
+
+    # reverse
+    nums.reverse()
+    print(nums[0])
+
+    # copy - returns list[T]
+    copied: list[int] = nums.copy()
+    print(len(copied))
+
+    # clear
+    nums.clear()
+    print(len(nums))
+    print(len(copied))