Raise the mise floor to 2026.7.8 (fleet lockstep)

Bumps this repo's vendored floor pair — min_version in .mise.toml and
mise_min_version in bin/setup — in lockstep with the fleet-wide raise to
the first mise containing jdx/mise#11034 (transport-agnostic repo-origin
comparison), which the docker-dev-origin v2 setup block relies on.

The literal is provisional on the first PUBLISHED qualifying release:
the v2026.7.8 tag contains the fix, but its release builds have failed
(deterministic macos-arm64 PGO mismatch) — re-literal before merge if a
later release publishes first. Setup upgrades mise in place, so
un-upgraded machines converge on their next bin/setup run; until then a
raised .mise.toml floor errors on every mise invocation in this checkout
(announce before landing).

Author: jeremy

.mise.toml

@@ -1,4 +1,4 @@
-min_version = "2026.7.5"
+min_version = "2026.7.8"
 
 [settings]
 idiomatic_version_file_enable_tools = ["ruby"]

bin/setup

@@ -39,7 +39,7 @@ step() {
   return $exit_code
 }
 
-mise_min_version="2026.7.5" # keep in lockstep with min_version in .mise.toml
+mise_min_version="2026.7.8" # keep in lockstep with min_version in .mise.toml
 
 mise_too_old() {
   local current="$(mise --version 2>/dev/null | awk '{ print $1; exit }')"