chore(v1): raise Node floor to >=22 and add codeman bin alias

- engines.node >=18 -> >=22 (Node 18/20 are EOL; CI only tests 22; the start script + systemd unit use NODE_COMPILE_CACHE which needs 22.1+). Updates the README badge and CLAUDE.md requirements to match.
- bin: add a 'codeman' alias alongside 'aicodeman' so 'npm i -g aicodeman' provides the 'codeman' command every doc/symlink references (program.name is already 'codeman'; the published package name stays 'aicodeman').

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

package.json

@@ -6,7 +6,8 @@
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
   "bin": {
-    "aicodeman": "./dist/index.js"
+    "aicodeman": "./dist/index.js",
+    "codeman": "./dist/index.js"
   },
   "scripts": {
     "postinstall": "node scripts/postinstall.js",
@@ -119,7 +120,7 @@
     }
   },
   "engines": {
-    "node": ">=18.0.0"
+    "node": ">=22.0.0"
   },
   "repository": {
     "type": "git",