Persist bash history and bake shell quality-of-life defaults

Two changes that address a longstanding frustration: bash history is
lost on every container recreate, and the container's ~/.bashrc and
~/.inputrc are stock Debian (no history tuning, no prefix search on
arrow keys, no integrations).

Added a named volume 'devbox-shell-history' mounted at ~/.cache/bash
with HISTFILE pointing there; history now survives 'docker compose up
--force-recreate'. The volume is added to both docker-compose.yml and
docker-compose.shared.yml, and ~/.cache/bash is registered in the
entrypoint ownership-fix loop per the AGENTS.md convention.

Baked rootfs/home/developer/.bash_aliases (sourced automatically by
Debian's default ~/.bashrc) and rootfs/home/developer/.inputrc into
the image. They give new containers: 100k-entry timestamped dedup
history with per-prompt flush, Up/Down arrow prefix history search,
case-insensitive coloured completion, aliases that prefer eza and
bat when present, git shortcuts, interactive rm/mv/cp, zoxide and
fzf (via 'fzf --bash') integration, and a [devbox] prompt marker.
The fzf integration uses 'fzf --bash' because we install fzf from
GitHub releases, not apt — the apt-path key-bindings aren't present.

Users who prefer their host's own shell config can uncomment two
commented bind-mount lines in docker-compose.yml to shadow the
baked defaults.

docker-compose.yml

@@ -52,6 +52,16 @@ services:
       # Optional: persist opencode TUI settings (theme, toggles, etc.)
       - devbox-state:/home/developer/.local/state/opencode
 
+      # Persist bash history across container recreations.
+      # Without this, ~/.bash_history is lost on 'docker compose up --force-recreate'.
+      - devbox-shell-history:/home/developer/.cache/bash
+
+      # Optional: override baked shell defaults with your host's rc files.
+      # The image ships sensible defaults (history tuning, prefix-search on
+      # Up/Down arrows, fzf/zoxide integration). Uncomment to use your own:
+      # - ~/.bash_aliases:/home/developer/.bash_aliases:ro
+      # - ~/.inputrc:/home/developer/.inputrc:ro
+
       # Optional: persist uv data (Python installs, tool installs)
       # Without this, 'uv python install' must be re-run after container removal.
       - devbox-uv:/home/developer/.local/share/uv
@@ -70,6 +80,7 @@ services:
 volumes:
   devbox-data:
   devbox-state:
+  devbox-shell-history:
   devbox-uv:
   # devbox-rustup:
   # devbox-cargo: