[log] Add debug logging to proxy/response_transform.go (#7739)

Add 5 debug log calls to `unwrapSingleObject` and `replaceNodesArray` in
`internal/proxy/response_transform.go`, reusing the existing
`logTransform` logger (`logger.New("proxy:response_transform")`).

## Changes

**`unwrapSingleObject`** – traces the 5 distinct code paths this
function takes when deciding how to reshape a GitHub API response after
DIFC filtering:

| Path | New log call |
|---|---|
| Wrapped empty array restored to top-level | `logTransform.Print("...
restoring wrapped empty array ...")` |
| Wrapped array matches original, restored | `logTransform.Printf("...
restoring wrapped array ..., len=%d")` |
| Search envelope skipped (`total_count` present) |
`logTransform.Print("... skipping search envelope ...")` |
| GraphQL response envelope skipped (`data` present) |
`logTransform.Print("... skipping GraphQL response envelope ...")` |
| Single-element filtered array unwrapped | `logTransform.Print("...
unwrapping single-element filtered array ...")` |

**`replaceNodesArray`** – logs which key (`nodes` or `edges`) was
replaced and how many DIFC-accessible items remain:

```
logTransform.Printf("replaceNodesArray: replacing %q array with %d accessible item(s)", key, len(items))
```

## Validation

- `go build ./...` ✅
- `go test ./...` ✅ (all 25 packages)
- `go vet ./...` ✅
- No import cycles — `proxy` is a higher-level package that safely
imports `logger`
- No side effects in log arguments — all values are already-computed
locals

## Activation

```bash
DEBUG=proxy:* ./awmg --config config.toml
```




> [!WARNING]
> <details>
> <summary>Firewall blocked 1 domain</summary>
>
> The following domain was blocked by the firewall during workflow
execution:
>
> - `index.crates.io`
>> To allow these domains, add them to the `network.allowed` list in
your workflow frontmatter:
>
> ```yaml
> network:
>   allowed:
>     - defaults
>     - "index.crates.io"
> ```
>
> See [Network
Configuration](https://github.github.com/gh-aw/reference/network/) for
more information.
>
> </details>


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Author: lpcox

internal/proxy/response_transform.go

@@ -59,9 +59,11 @@ func unwrapSingleObject(originalData interface{}, filteredData interface{}) inte
 			if wrapped, ok := arr[0].([]interface{}); ok &&
 				len(wrapped) == len(originalArray) {
 				if len(wrapped) == 0 {
+					logTransform.Print("unwrapSingleObject: restoring wrapped empty array to original top-level shape")
 					return wrapped
 				}
 				if reflect.DeepEqual(wrapped, originalArray) {
+					logTransform.Printf("unwrapSingleObject: restoring wrapped array to original top-level shape, len=%d", len(wrapped))
 					return wrapped
 				}
 			}
@@ -75,14 +77,17 @@ func unwrapSingleObject(originalData interface{}, filteredData interface{}) inte
 	}
 	// Don't unwrap search envelopes (handled by rewrapSearchResponse)
 	if _, hasTotalCount := original["total_count"]; hasTotalCount {
+		logTransform.Print("unwrapSingleObject: skipping search envelope (has total_count field)")
 		return filteredData
 	}
 	// Don't unwrap GraphQL responses (handled separately)
 	if _, hasData := original["data"]; hasData {
+		logTransform.Print("unwrapSingleObject: skipping GraphQL response envelope (has data field)")
 		return filteredData
 	}
 	// If filtered result is a single-element array, unwrap to match original shape
 	if arr, ok := filteredData.([]interface{}); ok && len(arr) == 1 {
+		logTransform.Print("unwrapSingleObject: unwrapping single-element filtered array to match original object shape")
 		return arr[0]
 	}
 	return filteredData
@@ -143,6 +148,7 @@ func replaceNodesArray(v interface{}, items []interface{}) bool {
 	}
 	for _, key := range []string{"nodes", "edges"} {
 		if _, ok := obj[key]; ok {
+			logTransform.Printf("replaceNodesArray: replacing %q array with %d accessible item(s)", key, len(items))
 			obj[key] = items
 			if _, ok := obj["totalCount"]; ok {
 				obj["totalCount"] = float64(len(items))