v0.3.0 — the Hush handoff gets a real KEY input

v0.3.0 — the Hush handoff gets a real KEY input

The blue wire is now the sanctioned route for Hush's clean-confidence matte:

• A "Matte" mask input — Resolve feeds it from the node's blue KEY
  input on the color page. Wire Hush's key output (node right-click → OFX
  Alpha → Enable) straight into it; the matte travels its own wire and never
  touches the RGB path, so nothing can unpremultiply the picture. Read
  robustly as max(luma, alpha), whichever way the host delivers the key.
• Use Incoming Matte keys the grain on that wire when connected, and
  falls back to the incoming image alpha (Hush 3.7.2's in-band export, the
  Fusion-page mode) when it isn't.
• Consume-on-use: whenever Use Incoming Matte is on, Speak forces its
  output alpha opaque — the matte is consumed at its consumer and never rides
  further downstream, where host alpha math would otherwise touch the grain.
  Off = uniform grain, alpha passes through untouched.
• The tooltip now carries the full three-step color-page recipe.

Verified: output alpha opaque everywhere; grain ~290× stronger where the
matte is 1 vs 0; Metal/OpenCL parity green (SpeakParams re-pinned at 384B).

Asset note: -ci-unsigned is an ad-hoc-signed dev build (right-click →
Open past Gatekeeper). Signed + notarized installers follow from the signing
machine.