Default `!md` type should set `binary = false` so markdown renders inline

[sfriedenberg-etsy]

Problem

The default !md type created at genesis has its binary setting such that der show -format text <md-zettel> returns the hyphence-framed metadata block instead of rendering the markdown blob body inline.

Observed: der show -format text mariah_carey/bottlecaps returned

---
# milestone 2 instructions
@ blake2b256-z3c6...
! md@ed25519_sig-...
---

i.e. the metadata frame, not the rendered body.

Fix

Set the default markdown type's binary = false in the genesis default-type definition (the embedded default !md type; see the genesis default-type construction around internal/foxtrot/env_repo/genesis.go and the type_blobs binary field).

Verify

BATS (deterministic): fresh-init repo, create an !md zettel with a known body, assert show -format text emits the body inline.

---

:clown: filed by Clown (0.4.0+cd38c2d) — built from cd38c2d