Packaging: the binary and package are inbuxa, INBUXA_* settings with STALWART_* fallback

- crates/main: package and [[bin]] renamed to inbuxa; homepage inbuxa.org;
  license AGPL-3.0-only (upstream is dual; the fork takes the AGPL).
- types::branding::env_var reads INBUXA_<name>, falling back to
  STALWART_<name> with a warning, for all nine server settings.
  STALWART_APP_ and STALWART_SPAM_* storage keys are unchanged.
- New-install default paths /var/lib/inbuxa and /var/log/inbuxa.
- Dockerfiles, systemd unit, launchd plist and AppArmor profile renamed.
- Upstream's .github moved to .github-upstream so none of it runs.
- install.sh stubbed: upstream's would install Stalwart.
- Two missed brand strings: the SMTP Received header and the utils user agent.

crates/main/Cargo.toml

@@ -1,17 +1,17 @@
 [package]
-name = "stalwart"
+name = "inbuxa"
 description = "INBUXA Mail and Collaboration Server, a fork of Stalwart"
 authors = [ "Stalwart Labs LLC <[email protected]>"]
-repository = "https://github.com/stalwartlabs/stalwart"
-homepage = "https://stalw.art"
+homepage = "https://inbuxa.org"
 keywords = ["imap", "jmap", "smtp", "email", "mail", "webdav", "server"]
 categories = ["email"]
-license = "AGPL-3.0-only OR LicenseRef-SEL"
+# Upstream offers AGPL-3.0-only OR LicenseRef-SEL; INBUXA takes the AGPL only.
+license = "AGPL-3.0-only"
 version = "0.16.22"
 edition = "2024"
 
 [[bin]]
-name = "stalwart"
+name = "inbuxa"
 path = "src/main.rs"
 
 [dependencies]