fix: repair the demo harness for the current manifest format

The demo has been unrunnable since eafd1c1f deleted bot-bottle.demo.json
as a pre-YAML-migration artifact. demo-setup.sh still copied that file
under `set -euo pipefail`, so demo.sh and demo-record.sh both exited
non-zero before launching anything.

Rebuild the fixtures in the current per-file Markdown format. Bottles
are only read from $HOME/.bot-bottle/bottles/ — manifest/index.py
ignores a bottles/ dir in CWD by design (PRD 0011) — so setup now
installs into real config and pairs every write with a .demo-backup
that teardown restores. Teardown compares content before removing, so
a second run cannot delete the user's restored original.

Point the DLP probe at the bottle's own example.org route rather than
api.anthropic.com/dlp-probe. The provider-injected anthropic route
defaults to `redact`, which would forward a scrubbed request instead of
refusing; the declared route sets outbound_on_match: block so probe 3
stays the hard 403 the demo is showing off. Left at the default
`supervise` it would instead hold the request open for up to 300s
awaiting operator approval and stall the recording.

Also drop the stale pipelock naming from the tape (egress is the
gateway's own scanner now), fix demo.sh's ./cli.py invocation, and
pre-warm Dockerfile.gateway instead of the removed Dockerfile.git-gate.

Refs #540

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/demo.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
-# Human-runnable demo wrapper. Stages the demo manifest and dummy
-# identity (see scripts/demo-setup.sh), launches `./cli.py start demo`
+# Human-runnable demo wrapper. Stages the demo bottle/agent and dummy
+# identity (see scripts/demo-setup.sh), launches `bot-bottle start demo`
 # interactively, then restores prior state. The recorded GIF
 # (docs/demo.gif) goes through the same flow via docs/demo.tape.
 #
@@ -26,4 +26,8 @@ fi
 bash scripts/demo-setup.sh
 trap 'bash scripts/demo-teardown.sh' EXIT
 
-./cli.py start demo
+# Pinned to the Docker backend: demo-setup.sh pre-warms the image graph
+# with `docker build`, and the demo is meant to run the same way on
+# every host rather than following the host default (Firecracker on KVM
+# Linux, Apple Container on macOS).
+BOT_BOTTLE_BACKEND=docker bot-bottle start demo