fix: update file reference on keyboard window navigation

Add WinEnter autocommand to selection tracking so keyboard navigation
(ctrl-h, ctrl-l, :wincmd) properly updates the file reference in Claude
Code. Previously only mouse clicks triggered updates.

The fix cancels pending debounce timers and uses a 10ms delay to ensure
window/buffer state is settled, matching the existing mouse handler
behavior.

Closes coder#2

Author: snirt

lua/claudecode/selection.lua

@@ -57,7 +57,7 @@ function M.disable()
 end
 
 ---Creates autocommands for tracking selections.
----Sets up listeners for CursorMoved, CursorMovedI, BufEnter, ModeChanged, and TextChanged events.
+---Sets up listeners for CursorMoved, CursorMovedI, BufEnter, WinEnter, ModeChanged, and TextChanged events.
 ---@local
 function M._create_autocommands()
   local group = vim.api.nvim_create_augroup("ClaudeCodeSelection", { clear = true })
@@ -82,6 +82,13 @@ function M._create_autocommands()
       M.on_text_changed()
     end,
   })
+
+  vim.api.nvim_create_autocmd("WinEnter", {
+    group = group,
+    callback = function()
+      M.on_win_enter()
+    end,
+  })
 end
 
 ---Sets up mouse event handler for capturing mouse-based selections.
@@ -149,6 +156,25 @@ function M.on_text_changed()
   M.debounce_update()
 end
 
+---Handles window enter events.
+---Triggers an immediate update to ensure file reference is sent on keyboard navigation.
+---Uses a small delay similar to mouse handler to ensure state is settled.
+function M.on_win_enter()
+  -- Cancel any pending debounce to avoid duplicate updates
+  if M.state.debounce_timer then
+    vim.loop.timer_stop(M.state.debounce_timer)
+    M.state.debounce_timer = nil
+  end
+
+  -- Use a small delay to ensure window/buffer state is settled
+  -- This mirrors the mouse handler behavior which works reliably
+  vim.defer_fn(function()
+    if M.state.tracking_enabled then
+      M.update_selection()
+    end
+  end, 10)
+end
+
 ---Debounces selection updates.
 ---Ensures that `update_selection` is not called too frequently by deferring
 ---its execution.