refactor(symfony-process): remove unused Process API surface

Since Process is php-native with no Rust-fidelity obligation (see
plugin-class-classification.md), this port only needs to cover what
Rust-ported Composer code actually calls. Made the pipes/process_utils
modules pub(crate) (nothing outside symfony/process used them) and
rebuilt with `--force-warn dead_code` (normally allowed workspace-wide)
to find genuinely unreachable methods: Process lost 17 methods, 5
constants, and a private clone helper; ExecutableFinder lost two unused
suffix setters; AbstractPipes lost handle_error, whose only caller (a
stream_select error-handler registration) was never wired up.

Removing several of those setters (set_pty, set_idle_timeout,
disable_output/enable_output, set_options) then left the fields they
used to write with no remaining writer, so they hold one constant value
on every reachable path: pty always false, idle_timeout always None,
output_disabled always false, options always {suppress_errors,
bypass_shell}. Audited by value (not just call-graph reachability) and
removed everything that depended on the now-constant value:

- pty: is_pty(), is_pty_supported(), the PTY descriptor branch in
  UnixPipes::get_descriptors(), and the now-unconstructed
  Descriptor::Pty variant in shirabe-php-shim (plus its proc_open
  match arm).
- idle_timeout: get_idle_timeout() and check_timeout()'s idle branch;
  ProcessTimedOutException collapses to the single reachable timeout
  type (dropped timeout_type/TYPE_GENERAL/TYPE_IDLE/is_general_timeout/
  is_idle_timeout/get_exceeded_timeout).
- output_disabled: is_output_disabled(), build_callback()'s disabled
  variant, get_descriptors()'s output_disabled term, and the
  always-false guard in read_pipes_for_output()/ProcessFailedException
  (its output section is now unconditional).
- options: Drop::drop()'s create_new_console branch can never fire
  (that key can no longer exist), so it always just stops the process.
- has_callback/last_output_time: left write-only once their only
  readers (the branches above) were gone.
- have_read_support: constant true once output_disabled collapsed, so
  removed from PipesInterface, UnixPipes (incl. its /dev/null
  null-stream branch), WindowsPipes, and Process::wait()'s dead guard.

No behavior change: every removed item/branch had zero callers, or was
constant on every reachable call site.

1 files changed, 0 insertions, 4 deletions

diff --git a/crates/shirabe-external-packages/src/symfony/process/pipes/abstract_pipes.rs b/crates/shirabe-external-packages/src/symfony/process/pipes/abstract_pipes.rs
index f9fb251d..8741926c 100644
--- a/crates/shirabe-external-packages/src/symfony/process/pipes/abstract_pipes.rs
+++ b/crates/shirabe-external-packages/src/symfony/process/pipes/abstract_pipes.rs
@@ -101,8 +101,4 @@ impl AbstractPipes {
 
         None
     }
-
-    pub fn handle_error(&mut self, _type: i64, msg: String) {
-        self.last_error = Some(msg);
-    }
 }