non negative line validation for comment server (#429)

* enforce non-negative validation for line in GH comment server

* include  .nonnegative() for startLine too

src/mcp/github-inline-comment-server.ts

@@ -41,12 +41,14 @@ server.tool(
       ),
     line: z
       .number()
+      .nonnegative()
       .optional()
       .describe(
         "Line number for single-line comments (required if startLine is not provided)",
       ),
     startLine: z
       .number()
+      .nonnegative()
       .optional()
       .describe(
         "Start line for multi-line comments (use with line parameter for the end line)",