Stop painting code green, and give each checkout its own emulator

Code is not a literal. Green is what this palette colours a literal, so
painting a whole fenced block green said the block *was* one -- and it
disagreed with the syntax highlighter a tool call's input already gets,
where green means a string and peach means a number. Code blocks and inline
spans now take the ordinary text colour; the monospace face and the tinted
background are what say "this is code", which is the part colour was not
doing. `codeColor` goes with it, since nothing else wanted a colour for
code. Where a literal really does appear inside code, the thing that should
colour it is a highlighter reading the code, not a rule about the container.

`run-android.sh` derives its AVD name from the checkout instead of defaulting
to a machine-wide `tdep`. That default made the emulator the one thing here
that cannot be worked on in parallel: two clones of this repo meant asking
whoever had it, waiting, and handing it back, and installing onto a running
one takes the foreground from whatever they were looking at. Derived rather
than written down, so neither clone names the other's, and `AVD_NAME=` still
overrides for sharing one deliberately.

Also: two things reported as markdown defects yesterday were not defects,
and are worth recording so nobody fixes them twice. The table is not
clipped -- it scrolls horizontally, which the renderer does whenever the
columns are wider than the screen; a screenshot of one looks exactly like a
clipped table, and swiping it shows the rest. The paragraph that appeared to
break around an inline code span was an artifact of how the test text was
sent through the echo driver, not of the renderer: sent as one message it
flows correctly.

app/run-android.sh

@@ -9,15 +9,22 @@ set -eu
 
 APP_ID="com.example.aiapp"
 
-# The AVD shared by this machine's Android projects -- one emulator, not
-# one per repo. Override with AVD_NAME=... elsewhere.
-AVD_NAME="${AVD_NAME:-tdep}"
 DEVICE_PROFILE="${DEVICE_PROFILE:-pixel_10}"
 SYSTEM_IMAGE="${SYSTEM_IMAGE:-system-images;android-36;google_apis;x86_64}"
 
 SCRIPT_DIR=$(cd "$(dirname "$0")" && pwd)
 cd "$SCRIPT_DIR"
 
+# One AVD per checkout, named after it -- so two clones of this repo, or a
+# clone and a worktree, each get their own rather than fighting over one.
+# This used to default to a machine-wide "tdep", which made the emulator the
+# one thing here that could not be worked on in parallel: taking it meant
+# asking whoever had it, waiting, and handing it back, and installing onto a
+# running one steals the foreground from whatever they were looking at.
+# Derived rather than written down, so neither clone names the other's.
+# Override with AVD_NAME=... to share one deliberately.
+AVD_NAME="${AVD_NAME:-$(basename "$(dirname "$SCRIPT_DIR")")}"
+
 # shellcheck source=./android-env.sh
 . ./android-env.sh