Fix Slack Windows app name to match registry (#37948)

## Summary

Fixes the app name in the Slack Windows Fleet-maintained app query to
match the actual Windows registry value.

## Issue

The generated query was using `Slack` as the app name, but Windows
registry shows the app name as `Slack (Machine - MSI)`. This caused a
mismatch preventing Fleet from properly matching the installed software
with the Fleet-maintained app.

## Changes

- Updated `unique_identifier` in `inputs/winget/slack.json` from
`"Slack"` to `"Slack (Machine - MSI)"`
- Regenerated output manifest with corrected query
- Version updated to 4.47.69 (latest available)

## Test plan

- [x] Verify the query matches actual Windows registry value on a test
host
- [x] Confirm Fleet can now properly match installed Slack software

ee/maintained-apps/inputs/winget/slack.json

@@ -2,7 +2,7 @@
   "name": "Slack",
   "slug": "slack/windows",
   "package_identifier": "SlackTechnologies.Slack",
-  "unique_identifier": "Slack",
+  "unique_identifier": "Slack (Machine - MSI)",
   "installer_arch": "x64",
   "installer_type": "msi",
   "installer_scope": "machine",

ee/maintained-apps/outputs/slack/windows.json

@@ -3,7 +3,7 @@
     {
       "version": "4.47.69",
       "queries": {
-        "exists": "SELECT 1 FROM programs WHERE name = 'Slack' AND publisher = 'Slack Technologies Inc.';"
+        "exists": "SELECT 1 FROM programs WHERE name = 'Slack (Machine - MSI)' AND publisher = 'Slack Technologies Inc.';"
       },
       "installer_url": "https://downloads.slack-edge.com/desktop-releases/windows/x64/4.47.69/slack-standalone-4.47.69.0.msi",
       "install_script_ref": "8959087b",