Add web, state, and backup sections to config template

- [web]: port and public fqdn for the daemon (Caddy proxies from a
  separate jail); port defaults to 8080
- [state]: daemon pidfile and logs directory, default ~/.config/rpn
- [backup]: timestamped dumps for rpnc db backup, default
  ~/.config/rpn/backups; rpnc db restore looks here by default
- cli.md: document the optional positional path and the directory
  defaults for db backup/restore

Documentation/cli.md

@@ -140,6 +140,7 @@ The following decisions were made while designing the CLI command structure:
 - **Customer create**: Uses flags `--id` and `--name`.
 - **File import**: Takes a positional path to the source file; v1 accepts epsilon TSV files only (tsdrms xlsx and subfranchise PDF are future work).
 - **File export**: Takes a positional filename; `--format` selects the target export format, `raw` being a byte-faithful copy of the original source.
+- **Db backup / restore**: Take an optional positional file path; default to the configured backup directory (the latest dump for restore).
 - **Invoice scope**: outgoing fuel invoices only; tsdrms/subfranchise data feeds the bookkeeping/voucher feature, never invoicing.
 - **Invoice create**: Uses flags `--batch`, `--from`, `--to`, `--customer`, and `--all`. The caller must supply either `--batch` or a `--from`/`--to` date range, and either `--customer` or `--all`. `--all` fans out to one invoice per customer found in the period.
 - **Invoice send**: Takes a positional `id`; the only status transition in v1.