fix: use SDK RawJSON() for -o json output to avoid zero values

[rgarcia]

Summary

• When using -o json, the CLI was re-marshaling SDK response structs with json.MarshalIndent(), which included Go zero values for fields not present in the API response (e.g., deleted_at, persistence, profile, viewport)
• Now uses the SDK's RawJSON() method which preserves the original API response, only outputting fields that were actually returned
• Adds PrintPrettyJSON and PrintPrettyJSONSlice helpers in pkg/util/json.go that pretty-print the raw JSON from SDK response types

Before

{
  "cdp_ws_url": "wss://...",
  "created_at": "2026-01-12T02:41:42.658978979Z",
  "session_id": "wvmx4yt5afram2xobclje52x",
  "timeout_seconds": 60,
  "deleted_at": "0001-01-01T00:00:00Z",
  "kiosk_mode": false,
  "persistence": {"id": ""},
  "profile": {"id": "", "created_at": "0001-01-01T00:00:00Z", ...},
  "viewport": {"height": 0, "width": 0, "refresh_rate": 0}
}

After

{
  "browser_live_view_url": "https://...",
  "cdp_ws_url": "wss://...",
  "created_at": "2026-01-12T02:49:16.736473188Z",
  "headless": false,
  "session_id": "tpuq0sl28j5d8par13mqo79d",
  "stealth": false,
  "timeout_seconds": 60
}

Test plan

• All existing tests pass (make test)
• Tested kernel browsers create --output json - no zero-value fields
• Tested kernel browsers list --output json - no zero-value fields

---

Note

Standardizes --output json to pretty-print the original API response using SDK RawJSON() instead of re-marshaling Go structs.

• Adds pkg/util/json.go with PrintPrettyJSON and PrintPrettyJSONSlice helpers that indent raw SDK JSON
• Refactors JSON output across commands (app, deploy history, browser-pools, browsers incl. replays/process/fs, extensions, proxies) to use the new helpers; consistent empty slice handling
• Special-case browsers view to emit { "liveViewUrl": ... } with proper JSON escaping
• Updates tests (browsers_test.go) to validate pretty JSON output using populated RawJSON()

^{Written by Cursor Bugbot for commit beccbd7. This will update automatically on new commits. Configure here.}

[tembo]

Nice cleanup overall — switching -o json to the SDK’s RawJSON() avoids the zero-value field noise, and the call sites read a lot cleaner.

Two small things in the new helpers:

• PrintPrettyJSON currently prints raw JSON on json.Indent failure and then returns nil. Since callers already propagate the error, returning the indent error would make unexpected/invalid RawJSON() failures easier to notice.
• PrintPrettyJSONSlice double-indents elements on the success path (prefixing in json.Indent and then adding another two spaces). Dropping the extra prefix keeps output consistent with the fallback branch and typical MarshalIndent formatting.

Everything else in the diff looks solid, and the test update to populate RawJSON() via json.Unmarshal makes sense.

[tembo]

PrintPrettyJSON currently swallows json.Indent errors and always returns nil, which makes it harder to detect when RawJSON() is unexpectedly empty/invalid. Since callers already return util.PrintPrettyJSON(...), it might be better to propagate the error.

Suggested change

	if err := json.Indent(&buf, []byte(raw), "", " "); err != nil {
	// If indentation fails, print the raw JSON as-is
	fmt.Println(raw)
	return nil
	}
	var buf bytes.Buffer
	if err := json.Indent(&buf, []byte(raw), "", " "); err != nil {
	return err
	}
	fmt.Println(buf.String())
	return nil

[tembo]

In PrintPrettyJSONSlice, the else path double-indents each element: json.Indent(..., prefix=" ") already prefixes the first line, and then you add another buf.WriteString(" ") before writing elemBuf. This makes the indent differ between the success and fallback branches.

Suggested change

	if err := json.Indent(&elemBuf, []byte(raw), " ", " "); err != nil {
	// Fallback to raw if indentation fails
	buf.WriteString(" ")
	buf.WriteString(raw)
	} else {
	buf.WriteString(" ")
	buf.Write(elemBuf.Bytes())
	}
	var elemBuf bytes.Buffer
	if err := json.Indent(&elemBuf, []byte(raw), " ", " "); err != nil {
	// Fallback to raw if indentation fails
	buf.WriteString(" ")
	buf.WriteString(raw)
	} else {
	buf.Write(elemBuf.Bytes())
	}