Opening a binary / non-UTF-8 file in the file manager threw "undefined is not
valid JSON". The editor bound the raw file bytes to its public $content
property; Livewire JSON-encodes the component snapshot, and invalid UTF-8 makes
PHP's json_encode return false, so the client received an empty response and
JSON.parse("undefined") failed (the trace in mergeNewSnapshot/deepClone).
Fixed at both layers: FleetService::readFile blanks the content when it detects
binary/non-UTF-8 (returns the binary flag instead), and FileEditor::load only
binds content for non-binary, non-oversize files. Binary/oversize files show
their existing notice; the snapshot is always valid UTF-8.
Tests: load blanks binary content (keeps the snapshot valid) and keeps valid
text content. 374 pass, Pint clean.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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