fix(dependency-resolver): query real PHP for ext-* version/loaded checks

Two shim gaps made the extension-related branches of solver-problem
messages wrong:

- phpversion($ext) with a non-empty extension can't be known statically
  (it's shirabe-php-shim's todo!()); Problem::get_missing_package_reason
  now calls shirabe_php_rpc::phpversion, the same RPC bridge
  platform::runtime::Runtime::get_extension_version already uses.
- extension_loaded's hardcoded allowlist was missing "pcre", a mandatory
  always-compiled-in PHP extension, so ext-pcre was misreported as
  "missing from your system" instead of "disabled by your platform
  config" whenever a platform override disabled it.

Also fix XdebugHandler::getAllIniFiles() always returning `[""]`
(a php-runtime stub): create_extension_hint()'s early-return guard
(`paths[0] empty && len==1`) fired unconditionally, silently dropping
the entire "To enable extensions..." hint from every solver-problem
message that mentions missing extensions. shirabe-external-packages
can't depend on shirabe-php-rpc (shirabe-php-rpc already depends on
shirabe-external-packages), so IniHelper::get_all() queries a new
get_all_ini_files RPC command directly instead of going through the
stub.

This exposed that XdebugHandler is never constructed with a name
because bin/composer's restart-without-Xdebug bootstrap was never
ported to main.rs, making COMPOSER_ORIGINAL_INIS-driven behavior
unreachable; documented with a TODO(phase-c) and updated
ini_helper_test.rs's ignore reasons (and ignored test_with_no_ini,
which only passed before by coincidence with the old stub's constant
output) to match.

3 files changed, 15 insertions, 4 deletions

diff --git a/crates/shirabe/src/dependency_resolver/problem.rs b/crates/shirabe/src/dependency_resolver/problem.rs
index 855638cf..5ff949a9 100644
--- a/crates/shirabe/src/dependency_resolver/problem.rs
+++ b/crates/shirabe/src/dependency_resolver/problem.rs
@@ -459,7 +459,9 @@ impl Problem {
                     Self::constraint_to_text(constraint)
                 );
 
-                let runtime_version = phpversion(&ext);
+                // Per-extension version info can't be known statically; query the real PHP
+                // runtime via the RPC bridge, same as platform::runtime::Runtime::get_extension_version.
+                let runtime_version = shirabe_php_rpc::phpversion(&ext);
                 let effective_version = match runtime_version {
                     None => "0".to_string(),
                     Some(ref v) => v.clone(),
diff --git a/crates/shirabe/src/main.rs b/crates/shirabe/src/main.rs
index 2ae6d903..6eb8e4cb 100644
--- a/crates/shirabe/src/main.rs
+++ b/crates/shirabe/src/main.rs
@@ -3,6 +3,13 @@
 use shirabe_php_shim::{PHP_ENV, PHP_SERVER};
 
 fn main() {
+    // TODO(phase-c): PHP: `$xdebug = new XdebugHandler('Composer'); $xdebug->check(); unset($xdebug);`
+    // (restart the process without Xdebug loaded, for performance) is not ported. Since no
+    // XdebugHandler is ever constructed, `self::$name` never gets set, so the
+    // COMPOSER_ORIGINAL_INIS-env-var branch of XdebugHandler::getAllIniFiles() (see
+    // shirabe-external-packages' xdebug_handler.rs and shirabe/src/util/ini_helper.rs) is
+    // unreachable in this port, not merely unexercised by current tests.
+
     // Take the $_ENV / $_SERVER snapshots before any putenv() mutates the real environment.
     // See `docs/dev/env-vars-porting.md` for details.
     std::sync::LazyLock::force(&PHP_ENV);
diff --git a/crates/shirabe/src/util/ini_helper.rs b/crates/shirabe/src/util/ini_helper.rs
index 57894113..c36b9189 100644
--- a/crates/shirabe/src/util/ini_helper.rs
+++ b/crates/shirabe/src/util/ini_helper.rs
@@ -1,13 +1,15 @@
 //! ref: composer/src/Composer/Util/IniHelper.php
 
-use shirabe_external_packages::composer::xdebug_handler::XdebugHandler;
-
 pub struct IniHelper;
 
 impl IniHelper {
     /// Returns an array of php.ini locations with at least one entry.
     pub fn get_all() -> Vec<String> {
-        XdebugHandler::get_all_ini_files()
+        // PHP: XdebugHandler::getAllIniFiles(). shirabe_external_packages::XdebugHandler's port
+        // of that method can't reach the PHP RPC bridge (shirabe-php-rpc already depends on
+        // shirabe-external-packages, so the reverse dependency would cycle), so query the real
+        // PHP runtime's loaded/scanned ini files here instead.
+        shirabe_php_rpc::get_all_ini_files()
     }
 
     /// Describes the location of the loaded php.ini file(s).