Add native image processor support to release binaries when sharp fallback is used

[xjdr-noumena]

Summary

Release package smoke currently accepts imageProcessorMode: "sharp-fallback" when the native image processor is not available. That is safe enough for smoke testing, but it means shipped binaries may use the slower/heavier fallback path instead of the intended native image processor.

Evidence

The package smoke native probe reports:

{
  "imageProcessorMode": "sharp-fallback",
  "imageProcessorWarnings": [
    "Native image processor not available, falling back to sharp"
  ]
}

This was observed during release/package smoke validation while working on the package minification fix.

Desired behavior

• Release binaries should include and load the native image processor where supported.
• Package smoke should continue to fail if the native path claims to be active while warnings are present.
• Once native image processor packaging is supported for Linux/macOS release targets, tighten package smoke so sharp-fallback is not accepted for those targets unless explicitly marked as an allowed degraded mode.

Acceptance criteria

• Linux x64 release package smoke reports imageProcessorMode: "native".
• macOS arm64 release package smoke reports imageProcessorMode: "native".
• macOS x64 release package smoke reports imageProcessorMode: "native".
• No native image processor warnings are emitted in package smoke for supported release targets.
• If any platform cannot support native image processing, the fallback is explicitly documented and surfaced as a typed packaging limitation, not silently accepted.