Use VBlank interrupt for Unbricked frame timing

[goodnamenotbad]

Fixes #157.

This updates the Unbricked examples so frame timing/main loops wait on the VBlank interrupt instead of busy-polling rLY.

Notes:

• Simple examples enable IE_VBLANK and use halt via WaitForVBlank.
• Serial-link examples also keep serial interrupts enabled, so they use a wVBlankDone flag to ignore serial wakeups while waiting for VBlank.
• Startup LCD-off waits still use rLY, since those are one-time initialization waits rather than frame timing/main-loop control.

Verification:

• git diff --check
• Built selected Unbricked examples with RGBDS v1.0.1 on Windows: objects, functions, input, collision, bricks, bcd, audio, title-screen, serial-link.

[quinnyo]

Wow, you arrived slightly too late #187
How could this, in 2026, possibly happen?

By the way, What are the chances!

[avivace]

Closing this for now, it's a large change and appears to be primarily AI-generated, which we don't have the bandwidth to review thoroughly. If you'd like to resubmit a more focused, human-driven contribution, we're happy to take a look.