Add bash tab-completion for setup.sh

./setup.sh mat<TAB> now completes to ./setup.sh mattermost, same for
flags. Service names are read fresh from services/*.sh on every
completion — never a hardcoded list, which would go stale the moment
a new service file gets added (matches this repo's own "adding a
service = adding one file, nothing generated" rule from CLAUDE.md).

Verified live: sourced the script and confirmed completions for "mat"
and "--li", and specifically confirmed "bes" resolves to "beszel" —
the service added earlier this same session — with zero changes
needed to the completion script itself, proving the list is genuinely
dynamic rather than something that looked right once and then rotted.

Self-locating via its own BASH_SOURCE path rather than a hardcoded
install directory, so it keeps working regardless of where the repo
is cloned. Works through a leading `sudo` via bash-completion's
standard sudo pass-through (enabled by default on Ubuntu).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01H4k6J1qXXyYxhGEgnJaMvn

README.md

@@ -141,11 +141,25 @@ echo "cloud-init.sh: repo cloned to $DEST — the setup wizard will launch on fi
 sudo ./setup.sh                        # interactive wizard
 sudo ./setup.sh caddy immich           # install specific services
 sudo ./setup.sh configure              # set site defaults (timezone, domain, Caddy network)
+sudo ./setup.sh filebrowser --remove   # remove a service (or: sudo ./setup.sh filebrowser remove)
 ./setup.sh --list                      # list all services grouped by category
 sudo ./setup.sh --dry-run immich       # preview without making changes
 sudo ./setup.sh --unattended base      # non-interactive, use defaults
 ```
 
+### Tab completion
+
+```bash
+echo "source $(pwd)/tools/setup-completion.bash" >> ~/.bashrc
+source ~/.bashrc
+```
+
+Then `./setup.sh mat<TAB>` completes to `./setup.sh mattermost` — same for
+flags (`--li<TAB>` → `--list`). Works with a leading `sudo` too. The service
+list is read fresh from `services/*.sh` on every completion, not a
+hardcoded list baked into the script — a service added since you last
+pulled shows up immediately, no re-running anything.
+
 ## What the wizard does
 
 **First run:**