fix: propagate ported exceptions instead of flattening them

`ProcessExecutor::execute_args` existed only to turn `execute`'s
`anyhow::Result` into an exit code of 1, so every one of its ~87 call
sites silently took the "command failed" branch on an error PHP would
have thrown. It is gone; callers use `execute` and propagate with `?`.
Where the enclosing function had no `Result` to propagate into, its
signature grew one, up to and including `Git::get_version`,
`Svn::binary_version`, `GitHub`/`GitLab`/`Bitbucket::authorize_oauth`,
`InitCommand::get_git_config` and `DiagnoseCommand::check_git`.

The VCS drivers had the same problem in the other direction: their
`get_contents` returned `Result<Response, Box<TransportException>>`, a
type too narrow for the PHP method, which lets any Throwable out of the
`catch (TransportException $e)` block. Every non-transport error was
therefore rewritten into a `TransportException` with code 0, which the
callers switch on. They now return
`anyhow::Result<Result<Response, Box<TransportException>>>`: the outer
`Result` carries what PHP does not catch, the inner one the exception
the drivers handle.

That signature also restores `GitLabDriver::getContents`: the 400/401
`TransportException`s it raises to force authentication are thrown
inside its own `try` block and handled by its own `catch`, but the port
returned them straight to the caller, so the authentication flow behind
them never ran.

`impl_php_exception!` gains `From<Box<$ty>> for anyhow::Error` so a
caught exception can be re-propagated with `?`.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/crates/shirabe/src/util/auth_helper.rs b/crates/shirabe/src/util/auth_helper.rs
index 72f50aa3..5e6ea16e 100644
--- a/crates/shirabe/src/util/auth_helper.rs
+++ b/crates/shirabe/src/util/auth_helper.rs
@@ -213,7 +213,7 @@ impl AuthHelper {
                 }
             }
 
-            if !git_hub_util.authorize_oauth(origin)
+            if !git_hub_util.authorize_oauth(origin)?
                 && (!self.io.is_interactive()
                     || !git_hub_util.authorize_oauth_interactively(origin, Some(&message))?)
             {
@@ -257,7 +257,7 @@ impl AuthHelper {
             }
 
             let scheme = parse_url(url).and_then(|parsed| parsed.scheme);
-            if !git_lab_util.authorize_oauth(origin)
+            if !git_lab_util.authorize_oauth(origin)?
                 && (!self.io.is_interactive()
                     || !git_lab_util.authorize_oauth_interactively(
                         scheme.as_deref().unwrap_or(""),
@@ -337,7 +337,7 @@ impl AuthHelper {
                 );
                 let mut bit_bucket_util =
                     Bitbucket::new(self.io.clone(), self.config.clone(), None, None, None)?;
-                if !bit_bucket_util.authorize_oauth(&origin)
+                if !bit_bucket_util.authorize_oauth(&origin)?
                     && (!self.io.is_interactive()
                         || !bit_bucket_util
                             .authorize_oauth_interactively(&origin, Some(&message))?)