fix: correct off-by-one indexing error in openFile text pattern search

Address Copilot review comment: when searching for endText pattern,
line_idx is already the correct 1-based index for the lines array,
so accessing lines[line_idx + 1] was incorrect.

Changed to lines[line_idx] to access the current line directly.

Change-Id: I05853ff183ef8f3e5df2863d2184a0cb58cb7e65
Signed-off-by: Thomas Kosiewski <tk@coder.com>

Author: ThomasK33

lua/claudecode/tools/open_file.lua

@@ -200,7 +200,7 @@ local function handler(params)
       -- Find end text if provided
       if params.endText then
         for line_idx = start_line_idx + 1, #lines do
-          local line = lines[line_idx + 1] -- Convert back to 1-based for lines array
+          local line = lines[line_idx] -- Access current line directly
           if line then
             local col_idx = string.find(line, params.endText, 1, true)
             if col_idx then