feat(installer): add --locale flag for translated docs installation

Adds `--locale <code>` support to the ECC installer so users can install
localized reference docs (agents, commands, skills, rules) into
`~/.claude/docs/<locale>/` alongside the existing English installation.

Changes:
- manifests/install-modules.json: add 8 locale doc modules (docs-ja-JP,
  docs-zh-CN, docs-ko-KR, docs-pt-BR, docs-ru, docs-tr, docs-vi-VN,
  docs-zh-TW), each with kind="docs" and defaultInstall=false
- manifests/install-components.json: add 8 locale: components mapping to
  the new modules
- scripts/lib/install-manifests.js: add locale: family prefix,
  SUPPORTED_LOCALES, LOCALE_ALIAS_TO_COMPONENT_ID (with aliases like
  ja=ja-JP, zh=zh-CN, ko=ko-KR), and listSupportedLocales()
- scripts/lib/install/request.js: add --locale flag to parseInstallArgs(),
  resolve locale alias → component ID in normalizeInstallRequest(), throw
  on unsupported locale codes
- scripts/lib/install-targets/claude-home.js: map docs/<locale>/ source
  paths to ~/.claude/docs/<locale>/ destination (side-by-side, no overwrite
  of English files)
- scripts/install-apply.js: import listSupportedLocales, add --locale
  usage line and available locales list to --help output

Usage examples:
  ./install.sh --locale ja                    # Japanese docs only
  ./install.sh --profile core --locale zh-CN  # core profile + zh-CN docs
  ./install.sh typescript --locale ja         # legacy + locale (errors)

scripts/install-apply.js

@@ -10,6 +10,7 @@ const os = require('os');
 const {
   SUPPORTED_INSTALL_TARGETS,
   listLegacyCompatibilityLanguages,
+  listSupportedLocales,
 } = require('./lib/install-manifests');
 const {
   LEGACY_INSTALL_TARGETS,
@@ -19,12 +20,14 @@ const {
 
 function getHelpText() {
   const languages = listLegacyCompatibilityLanguages();
+  const locales = listSupportedLocales();
 
   return `
 Usage: install.sh [--target <${LEGACY_INSTALL_TARGETS.join('|')}>] [--dry-run] [--json] <language> [<language> ...]
        install.sh [--target <${SUPPORTED_INSTALL_TARGETS.join('|')}>] [--dry-run] [--json] --profile <name> [--with <component>]... [--without <component>]...
        install.sh [--target <${SUPPORTED_INSTALL_TARGETS.join('|')}>] [--dry-run] [--json] --modules <id,id,...> [--with <component>]... [--without <component>]...
        install.sh [--target <${SUPPORTED_INSTALL_TARGETS.join('|')}>] [--dry-run] [--json] --skills <skill-id[,skill-id...]>
+       install.sh [--target claude] [--dry-run] [--json] --locale <locale-code>
        install.sh [--dry-run] [--json] --config <path>
 
 Targets:
@@ -46,6 +49,8 @@ Options:
   --skills <ids>      Install one or more skill directories by ID, e.g. continuous-learning-v2
   --without <component>
                       Exclude a user-facing install component
+  --locale <code>     Install translated docs to ~/.claude/docs/<locale>/
+                      (claude target only; can be combined with --profile or --with)
   --config <path>     Load install intent from ecc-install.json
   --dry-run    Show the install plan without copying files
   --json       Emit machine-readable plan/result JSON
@@ -53,6 +58,9 @@ Options:
 
 Available languages:
 ${languages.map(language => `  - ${language}`).join('\n')}
+
+Available locales (--locale):
+${locales.map(locale => `  - ${locale}`).join('\n')}
 `;
 }
 

scripts/lib/install-manifests.js

@@ -12,7 +12,28 @@ const COMPONENT_FAMILY_PREFIXES = {
   capability: 'capability:',
   agent: 'agent:',
   skill: 'skill:',
+  locale: 'locale:',
 };
+const SUPPORTED_LOCALES = Object.freeze(['ja', 'zh-CN', 'ko-KR', 'pt-BR', 'ru', 'tr', 'vi-VN', 'zh-TW']);
+const LOCALE_ALIAS_TO_COMPONENT_ID = Object.freeze({
+  'ja': 'locale:ja',
+  'ja-JP': 'locale:ja',
+  'zh-CN': 'locale:zh-CN',
+  'zh': 'locale:zh-CN',
+  'ko-KR': 'locale:ko-KR',
+  'ko': 'locale:ko-KR',
+  'pt-BR': 'locale:pt-BR',
+  'pt': 'locale:pt-BR',
+  'ru': 'locale:ru',
+  'tr': 'locale:tr',
+  'vi-VN': 'locale:vi-VN',
+  'vi': 'locale:vi-VN',
+  'zh-TW': 'locale:zh-TW',
+});
+
+function listSupportedLocales() {
+  return [...SUPPORTED_LOCALES];
+}
 const LEGACY_COMPAT_BASE_MODULE_IDS_BY_TARGET = Object.freeze({
   claude: [
     'rules-core',
@@ -607,11 +628,14 @@ function resolveInstallPlan(options = {}) {
 module.exports = {
   DEFAULT_REPO_ROOT,
   SUPPORTED_INSTALL_TARGETS,
+  SUPPORTED_LOCALES,
+  LOCALE_ALIAS_TO_COMPONENT_ID,
   getManifestPaths,
   loadInstallManifests,
   getInstallComponent,
   listInstallComponents,
   listLegacyCompatibilityLanguages,
+  listSupportedLocales,
   listInstallModules,
   listInstallProfiles,
   resolveInstallPlan,

scripts/lib/install-targets/claude-home.js

@@ -39,6 +39,10 @@ function getClaudeManagedDestinationPath(adapter, sourceRelativePath, input) {
     );
   }
 
+  if (normalizedSourcePath === 'docs' || normalizedSourcePath.startsWith('docs/')) {
+    return path.join(targetRoot, normalizedSourcePath);
+  }
+
   return null;
 }
 

scripts/lib/install/request.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const { validateInstallModuleIds } = require('../install-manifests');
+const { validateInstallModuleIds, LOCALE_ALIAS_TO_COMPONENT_ID, listSupportedLocales } = require('../install-manifests');
 
 const LEGACY_INSTALL_TARGETS = ['claude', 'cursor', 'antigravity'];
 
@@ -27,6 +27,7 @@ function parseInstallArgs(argv) {
     includeComponentIds: [],
     excludeComponentIds: [],
     languages: [],
+    locale: null,
   };
 
   for (let index = 0; index < args.length; index += 1) {
@@ -60,6 +61,9 @@ function parseInstallArgs(argv) {
         parsed.excludeComponentIds.push(componentId.trim());
       }
       index += 1;
+    } else if (arg === '--locale') {
+      parsed.locale = args[index + 1] || null;
+      index += 1;
     } else if (arg === '--dry-run') {
       parsed.dryRun = true;
     } else if (arg === '--json') {
@@ -84,9 +88,17 @@ function normalizeInstallRequest(options = {}) {
   const moduleIds = validateInstallModuleIds(
     dedupeStrings([...(config?.moduleIds || []), ...(options.moduleIds || [])])
   );
+  const locale = options.locale || config?.locale || null;
+  const localeComponentId = locale ? LOCALE_ALIAS_TO_COMPONENT_ID[locale] : null;
+  if (locale && !localeComponentId) {
+    throw new Error(
+      `Unsupported locale: "${locale}". Supported locales: ${listSupportedLocales().join(', ')}`
+    );
+  }
   const includeComponentIds = dedupeStrings([
     ...(config?.includeComponentIds || []),
     ...(options.includeComponentIds || []),
+    ...(localeComponentId ? [localeComponentId] : []),
   ]);
   const excludeComponentIds = dedupeStrings([
     ...(config?.excludeComponentIds || []),
@@ -102,7 +114,7 @@ function normalizeInstallRequest(options = {}) {
 
   if (usingManifestMode && legacyLanguages.length > 0) {
     throw new Error(
-      'Legacy language arguments cannot be combined with --profile, --modules, --with, --without, or manifest config selections'
+      'Legacy language arguments cannot be combined with --profile, --modules, --with, --without, --locale, or manifest config selections'
     );
   }