ca-certs: generate install artifacts and improve certdata/trust-store compatibility

- stop committing generated man/completion files in contrib/
- generate man page and shell completions during Meson install via install-generated-docs.sh
- switch reqwest to native-tls and add Mozilla hg bootstrap certs with openssl fallback fetch
- make certdata sync use a temporary auto-cleaned workspace by default
- add BLFS/make-ca compatibility outputs and symlinks under /etc/pki and /etc/ssl
- validate extracted outputs are non-empty and add tests for temp sync output behavior

README.md

@@ -34,7 +34,7 @@ target/release/ca-certs
 
 ### Meson (packaging-friendly)
 
-Builds the Rust binary and installs the man page + shell completions from `contrib/`.
+Builds the Rust binary and generates man/completion artifacts during install.
 
 ```bash
 meson setup build
@@ -156,7 +156,7 @@ Run tests:
 cargo test
 ```
 
-The repository also includes a generated man page and shell completions under `contrib/`.
+Man page and shell completions are generated by `ca-certs gen-artifacts`.
 
 ## License