docs: sync README command sections with the actual command tree

[noamloewenstern]

Closes #76

The README's command sections had fallen behind the CLI. This syncs them with the actual command tree, verified by building from this branch and walking --help for every command group and subcommand (144 commands total).

Added:

• project create
• app create (public, github, deploy-key, dockerfile, dockerimage) with key flags
• app previews delete
• storage sections for app, database, and service
• database env (list/get/create/update/delete/sync)
• service create <type> and --list-types
• version
• a short section for the alpha init and firewall trees (feat(init,firewall): add WireGuard mesh bootstrap and coold firewall client (alpha, v5) #72), pointing to --help and llms-full.txt instead of duplicating their large flag surface

Fixed:

• Global Flags: removed --host and -f, --force, which aren't global flags on the current build; --force stays documented per-command
• database backup create: retention flag names (--retention-days-locally, --retention-max-storage-locally, --disable-local-backup, etc.)
• service env sync: removed the --preview flag it doesn't have
• env create/update/sync: added --runtime and --comment, noted the build-time/runtime defaults
• private-key add: takes a plain file path, not @filename
• deploy uuid/name/batch: --force has no -f shorthand (only deploy cancel does)

Also added app create and service create examples to the Examples section, adapted from the commands' own --help examples.

llms.txt/llms-full.txt: regenerated with go run ./coolify docs llms; no content changes, so they're not part of the diff.

Every line in the diff traces back to captured --help output; no invented flags.

[andrasbacsai]

Superseded by #79, which applies the README sync to the current v4.x head and includes the generated catalog refresh required by CI.