feat(core): add SourceResolver for backwards-compatible src/ → source/ migration

Introduces SourceResolver utility class with source/ → src/ → htdocs/
fallback chain, replacing hardcoded src/ references across 28 files.
This enables renaming root-level src/ to source/ in all repos while
maintaining backwards compatibility during the transition.

Phase 1: New lib/Enterprise/SourceResolver.php with resolve(),
resolveAbsolute(), globSource(), findUnderSource(), warnIfLegacy()
Phase 2: Updated 19 CLI/deploy tools to use SourceResolver
Phase 3: Updated 7 validator/lib files (McpServerPlugin,
PackageBuilder, RepositorySynchronizer, auto_detect_platform,
check_dolibarr_module, check_client_theme, check_structure)

Authored-by: Moko Consulting
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cli/version_check.php

@@ -18,7 +18,7 @@ declare(strict_types=1);
 
 require_once __DIR__ . '/../lib/Enterprise/CliFramework.php';
 
-use MokoEnterprise\CliFramework;
+use MokoEnterprise\{CliFramework, SourceResolver};
 
 class VersionCheckCli extends CliFramework
 {
@@ -77,7 +77,8 @@ class VersionCheckCli extends CliFramework
                 $versions['pyproject.toml'] = $m[1];
             }
         }
-        foreach (["{$root}/src/pkg_*.xml", "{$root}/src/*.xml", "{$root}/src/packages/*/*.xml", "{$root}/*.xml"] as $glob) {
+        $srcName = SourceResolver::resolve($root);
+        foreach (["{$root}/{$srcName}/pkg_*.xml", "{$root}/{$srcName}/*.xml", "{$root}/{$srcName}/packages/*/*.xml", "{$root}/*.xml"] as $glob) {
             foreach (glob($glob) ?: [] as $file) {
                 if (basename($file) === 'updates.xml') {
                     continue;