fix: CJK/Unicode wide character support (#13)

Set UTF-8 locale in all PTY spawn environments, add xterm-addon-unicode11
for proper double-width character measurement, and update LocalEchoOverlay
helpers to respect CJK character visual width in positioning, line wrapping,
and cursor placement.

Based on PR #13 by @TeigenZhang, adapted to current codebase structure.

Co-Authored-By: Tenggan Zhang <TeigenZhang@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "claudeman",
-  "version": "0.1600",
+  "version": "0.1618",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "claudeman",
-      "version": "0.1600",
+      "version": "0.1618",
       "hasInstallScript": true,
       "license": "MIT",
       "dependencies": {
@@ -20,6 +20,7 @@
         "uuid": "^10.0.0",
         "xterm": "^5.3.0",
         "xterm-addon-fit": "^0.8.0",
+        "xterm-addon-unicode11": "^0.6.0",
         "xterm-addon-webgl": "^0.16.0",
         "zod": "^4.3.6"
       },
@@ -4669,6 +4670,16 @@
         "xterm": "^5.0.0"
       }
     },
+    "node_modules/xterm-addon-unicode11": {
+      "version": "0.6.0",
+      "resolved": "https://registry.npmjs.org/xterm-addon-unicode11/-/xterm-addon-unicode11-0.6.0.tgz",
+      "integrity": "sha512-5pkb8YoS/deRtNqQRw8t640mu+Ga8B2MG3RXGQu0bwgcfr8XiXIRI880TWM49ICAHhTmnOLPzIIBIjEnCq7k2A==",
+      "deprecated": "This package is now deprecated. Move to @xterm/addon-unicode11 instead.",
+      "license": "MIT",
+      "peerDependencies": {
+        "xterm": "^5.0.0"
+      }
+    },
     "node_modules/xterm-addon-webgl": {
       "version": "0.16.0",
       "resolved": "https://registry.npmjs.org/xterm-addon-webgl/-/xterm-addon-webgl-0.16.0.tgz",