fix(comments): ensure filePath has leading slash for inline comments

Without a leading / in filePath, Azure DevOps does not set
changeTrackingId on the thread. This causes the web UI to show
'This file no longer exists in the latest pull request changes'
even though the file exists.

Verified against real Azure DevOps API:
- Without leading /: changeTrackingId is MISSING
- With leading /: changeTrackingId is set correctly

Added ensure_leading_slash/1 helper to normalize user input.

Author: gilbertwong96

lib/ado_cli/cli/pull_requests.ex

@@ -1187,6 +1187,9 @@ defmodule AdoCli.CLI.PullRequests do
     get_in(change, ["item", "path"]) || change["originalPath"] || change["path"] || "?"
   end
 
+  defp ensure_leading_slash("/" <> _ = path), do: path
+  defp ensure_leading_slash(path), do: "/#{path}"
+
   defp change_type(change) do
     # Azure DevOps can return changeType as string ("add") or integer (1).
     # Normalize to integer first, then map to display string.
@@ -2100,6 +2103,10 @@ defmodule AdoCli.CLI.PullRequests do
 
     path = "/#{project}/_apis/git/repositories/#{repo_id}/pullrequests/#{pr_id}/threads"
 
+    # Azure DevOps requires filePath with a leading /. Without it,
+    # changeTrackingId is missing and the web UI shows "file no longer exists".
+    canonical_path = ensure_leading_slash(file_path)
+
     body = %{
       "comments" => [
         %{
@@ -2110,15 +2117,15 @@ defmodule AdoCli.CLI.PullRequests do
       ],
       "status" => status,
       "threadContext" => %{
-        "filePath" => file_path,
+        "filePath" => canonical_path,
         "rightFileStart" => %{"line" => line, "offset" => 1},
         "rightFileEnd" => %{"line" => line, "offset" => 2}
       }
     }
 
     case Client.post(path, body) do
       {:ok, result} ->
-        render_add_result(result, "Comment added to #{file_path}:#{line}.", json?)
+        render_add_result(result, "Comment added to #{canonical_path}:#{line}.", json?)
 
       {:error, reason} ->
         bail(reason, parsed)

test/ado_cli/cli/pull_requests_test.exs

@@ -1021,7 +1021,7 @@ defmodule AdoCli.CLI.PullRequestsTest do
           ],
           "status" => "active",
           "threadContext" => %{
-            "filePath" => "src/foo.ex",
+            "filePath" => "/src/foo.ex",
             "rightFileStart" => %{"line" => 42, "offset" => 1},
             "rightFileEnd" => %{"line" => 42, "offset" => 2}
           }