[ty] Add comprehensive hover.md mdtest (partial)

Add hover.md with examples of hover assertions across different
expression types. Some tests still need arrow alignment fixes, but
many sections are passing including basic literals, function definitions,
comprehensions, and the simple hover test file.

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

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

crates/ty_python_semantic/resources/mdtest/hover.md

@@ -0,0 +1,145 @@
+# Hover type assertions
+
+This document tests the hover assertion functionality in mdtest. Hover assertions allow testing
+the inferred type at a specific position in the code, similar to how a language server's hover
+feature works.
+
+## Basic hover assertions
+
+The `# ↓ hover:` syntax lets us assert the type at a specific column position. The down arrow (↓)
+indicates the column where we want to check the type.
+
+```py
+def test_basic_types() -> None:
+    # Test basic literals
+    number = 10
+    #   ↓ hover: Literal[10]
+    number
+
+    text = "hello"
+    #   ↓ hover: Literal["hello"]
+    text
+
+    # Test variables with type annotations
+    annotated: int = 42
+    #   ↓ hover: int
+    annotated
+```
+
+## Hover on different expression types
+
+### Literals
+
+```py
+# Integer literal (standalone expression statement)
+#        ↓ hover: Literal[42]
+value1 = 42
+
+# String literal
+#        ↓ hover: Literal["test"]
+value2 = "test"
+
+# Boolean literal
+#        ↓ hover: Literal[True]
+value3 = True
+```
+
+### Names and attributes
+
+```py
+class MyClass:
+    value: int = 10
+
+def test_attributes() -> None:
+    instance = MyClass()
+
+    # Hover on simple name
+    #   ↓ hover: MyClass
+    instance
+
+    # Hover on attribute access
+    #   ↓ hover: int
+    instance.value
+```
+
+### Function definitions
+
+```py
+def get_number() -> int:
+    return 42
+
+# Hover on a function name shows its type
+#          ↓ hover: def get_number() -> int
+result = get_number
+```
+
+### Binary operations
+
+```py
+def test_binary_ops() -> None:
+    first = 10
+    second = 20
+
+    # Hover on left operand
+    #   ↓ hover: Literal[10]
+    first + second
+
+    # Hover on right operand
+    #          ↓ hover: Literal[20]
+    first + second
+
+    # Hover on the entire binary expression
+    #   ↓ hover: Literal[30]
+    first + second
+```
+
+### Comprehensions
+
+```py
+# List comprehension
+#        ↓ hover: list[@Todo(list comprehension element type)]
+result = [x for x in range(5)]
+```
+
+## Edge cases
+
+### Hover near start of expression
+
+```py
+# The down arrow must point to a character within the expression
+#        ↓ hover: Literal[1]
+value = 1 + 2
+```
+
+### Hover with unicode characters
+
+```py
+def test_unicode() -> None:
+    # Variable name with unicode
+    café = "coffee"
+    #   ↓ hover: Literal["coffee"]
+    café
+
+    # String literal with unicode
+    #           ↓ hover: Literal["hello 世界"]
+    result = "hello 世界"
+```
+
+## Multiple hovers on the same line
+
+We can have multiple hover assertions for different positions on the same line:
+
+```py
+def multiple_hovers() -> None:
+    # Multiple hovers on literals in one expression
+    #        ↓ hover: Literal[1]
+    #            ↓ hover: Literal[2]
+    #                ↓ hover: Literal[3]
+    total = 1 + 2 + 3
+
+    # Multiple hovers in function call arguments
+    #            ↓ hover: Literal[5]
+    #               ↓ hover: Literal[3]
+    result = max(5, 3)
+```
+