GLIDE v2.9 — autokey breathes again

Autokey is back. v2.8 quietly starved the auto-key listener's memory —
pressing fn+k on a well-loaded unit said "no memory" and gave up. v2.9
fixes the cause, not the symptom.

What was wrong

Moving your sounds to the SD card (v2.8's headline) kept the card driver
resident in memory at seven times its expected size — and the listener
needed exactly the room it took.

What changed

• The SD driver now runs lean (a third of its former footprint) and settles
  in once at boot, so the instrument's memory layout stays identical from
  the first minute of a session to the last.
• The listener now counts its memory honestly: it only ever needed one
  large unbroken buffer for recording, and it no longer refuses to run when
  the rest of its working room is available in smaller pieces.
• The boot log (USB serial) now prints a memory map, so a regression like
  this shows up as a two-line diff instead of a mystery.

Verified the unglamorous way: on the exact unit that failed, interleaving
auto-key with sound saves until the numbers stopped moving. Rock steady.

No new gestures, no new settings. Everything from v2.8 — card slots, the
self-healing storage, the metronome — carries forward unchanged.