fix(tools): improve read_lines out-of-bounds handling

- Return error only when entire requested range is outside file bounds
- Clamp to file end when only upper boundary exceeds file length
- Store original values for accurate error messages
- Apply same behavior for both direct calls and executor usage
- Improves robustness for agents requesting line ranges

Examples:
- '3-10' in 5-line file → returns lines 3-5 (clamped)
- '8-12' in 5-line file → returns error (entire range outside)
- '10' in 5-line file → returns error (single line outside)

Author: cellwebb

src/clippy/tools/read_lines.py

@@ -169,11 +169,19 @@ def parse_line_range(
             except ValueError:
                 return True, "", 1, total_lines
 
-    # Check if range is out of bounds (before clamping)
-    if start < 1 or end > total_lines:
+    # Store original values before clamping to check bounds
+    original_start = start
+    original_end = end
+
+    # Clamp to file bounds
+    start = max(1, start)
+    end = min(total_lines, end)
+
+    # Check if the entire requested range is outside file bounds
+    if original_end < 1 or original_start > total_lines:
         return (
             False,
-            f"Line range {range_spec} (resolved to {start}-{end}) is outside "
+            f"Line range {range_spec} (resolved to {original_start}-{original_end}) is outside "
             f"file bounds (file has {total_lines} lines)",
             0,
             0,