feat: multi-language support — PHP, Ruby, Perl, Go (binary-env)

- PHP: ghcr.io/fission/php-env, entrypoint main.php::handler
- Ruby: ghcr.io/fission/ruby-env, entrypoint handler (single-word)
- Perl: ghcr.io/fission/perl-env (version=1), sub {} return value
- Go: ghcr.io/fission/binary-env with pre-compiled binary (shell script placeholder)

Provider changes:
- package_resource: added main.php, main.rb, main.pl to source_dir candidates
- function_resource: relaxed entrypoint validation to allow PHP (::), Ruby, Perl (single-word)
- function_resource_test: updated BadFormat test to reflect new valid formats

.gitignore

@@ -8,6 +8,9 @@ bin/
 *.test
 *.out
 
+# Compiled function binaries (generated, not versioned)
+examples/*/dist/
+
 # Provider binaries
 terraform-provider-fission
 terraform-provider-fission_*