Improve icon selection and resizing in generate-icons.sh (#35258)

I ran into an app that only had a single 512 x 512 png icon resulting in
the `generate-icons.sh` script failing.

```
% bash tools/software/icons/generate-icons.sh -a /Applications/logioptionsplus.app  -s "logi-options+/darwin"
Error: 128x128 icon not found.
```

This should add some additional flexibility. 

<!-- Add the related story/sub-task/bug number, like Resolves #123, or
remove if NA -->
**Related issue:** Resolves #

# Checklist for submitter

If some of the following don't apply, delete the relevant line.

- [ ] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
See [Changes
files](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/guides/committing-changes.md#changes-files)
for more information.

- [ ] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements)
- [ ] If paths of existing endpoints are modified without backwards
compatibility, checked the frontend/CLI for any necessary changes

## Testing

- [ ] Added/updated automated tests
- [ ] Where appropriate, [automated tests simulate multiple hosts and
test for host
isolation](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/reference/patterns-backend.md#unit-testing)
(updates to one hosts's records do not affect another)

- [ ] QA'd all new/changed functionality manually

For unreleased bug fixes in a release candidate, one of:

- [ ] Confirmed that the fix is not expected to adversely impact load
test results
- [ ] Alerted the release DRI if additional load testing is needed

## Database migrations

- [ ] Checked schema for all modified table for columns that will
auto-update timestamps during migration.
- [ ] Confirmed that updating the timestamps is acceptable, and will not
cause unwanted side effects.
- [ ] Ensured the correct collation is explicitly set for character
columns (`COLLATE utf8mb4_unicode_ci`).

## New Fleet configuration settings

- [ ] Setting(s) is/are explicitly excluded from GitOps

If you didn't check the box above, follow this checklist for
GitOps-enabled settings:

- [ ] Verified that the setting is exported via `fleetctl
generate-gitops`
- [ ] Verified the setting is documented in a separate PR to [the GitOps
documentation](https://github.com/fleetdm/fleet/blob/main/docs/Configuration/yaml-files.md#L485)
- [ ] Verified that the setting is cleared on the server if it is not
supplied in a YAML file (or that it is documented as being optional)
- [ ] Verified that any relevant UI is disabled when GitOps mode is
enabled

## fleetd/orbit/Fleet Desktop

- [ ] Verified compatibility with the latest released version of Fleet
(see [Must
rule](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/workflows/fleetd-development-and-release-strategy.md))
- [ ] If the change applies to only one platform, confirmed that
`runtime.GOOS` is used as needed to isolate changes
- [ ] Verified that fleetd runs on macOS, Linux and Windows
- [ ] Verified auto-update works from the released version of component
to the new version (see [tools/tuf/test](../tools/tuf/test/README.md))

tools/software/icons/generate-icons.sh

@@ -78,14 +78,50 @@ ICON_DIR="$TMP_DIR/icons.iconset"
 mkdir -p "$ICON_DIR"
 iconutil -c iconset "$ICNS_PATH" -o "$ICON_DIR"
 
-# Find the 128x128 PNG
-ICON_128=$(find "$ICON_DIR" -name "*128x128.png" | head -n 1)
+# Debug: list all PNG files in iconset
+echo "Available icon files in iconset:"
+find "$ICON_DIR" -name "*.png" | sort || true
+
+# Find the 128x128 PNG (prefer exact 128x128, not @2x)
+ICON_128=$(find "$ICON_DIR" -name "*128x128.png" ! -name "*@2x*" | head -n 1)
 if [[ -z "$ICON_128" ]]; then
-  echo "Error: 128x128 icon not found."
+  # Fallback: try 128x128@2x (which is 256x256)
+  ICON_128=$(find "$ICON_DIR" -name "*128x128@2x.png" | head -n 1)
+fi
+if [[ -z "$ICON_128" ]]; then
+  # Fallback: try any icon with 128 in the name
+  ICON_128=$(find "$ICON_DIR" -name "*128*.png" | head -n 1)
+fi
+if [[ -z "$ICON_128" ]]; then
+  # Last resort: find the largest PNG (prefer larger sizes)
+  ICON_128=$(find "$ICON_DIR" -name "*.png" | sort -V | tail -n 1)
+fi
+
+if [[ -z "$ICON_128" ]]; then
+  echo "Error: No icon PNG files found in extracted iconset."
+  echo "ICON_DIR: $ICON_DIR"
   exit 1
 fi
+
 echo "Using icon for SVG and PNG: $ICON_128"
 
+# Check dimensions and resize to 128x128 if larger
+ICON_WIDTH=$(sips -g pixelWidth "$ICON_128" | grep pixelWidth | awk '{print $2}')
+ICON_HEIGHT=$(sips -g pixelHeight "$ICON_128" | grep pixelHeight | awk '{print $2}')
+echo "Icon dimensions: ${ICON_WIDTH}x${ICON_HEIGHT}"
+
+if [[ $ICON_WIDTH -gt 128 || $ICON_HEIGHT -gt 128 ]]; then
+  echo "Resizing icon from ${ICON_WIDTH}x${ICON_HEIGHT} to 128x128..."
+  RESIZED_ICON="$TMP_DIR/icon_128x128.png"
+  sips -z 128 128 "$ICON_128" --out "$RESIZED_ICON" > /dev/null 2>&1
+  if [[ -f "$RESIZED_ICON" ]]; then
+    ICON_128="$RESIZED_ICON"
+    echo "Resized icon saved to: $ICON_128"
+  else
+    echo "Warning: Failed to resize icon, using original"
+  fi
+fi
+
 # Generate SVG from 128 PNG
 WIDTH=32
 HEIGHT=32