fix: remove dead export, harden session-aliases, sync .cursor scripts

- Remove duplicate getAliasesPath() from utils.js (only used in
  session-aliases.js which has its own copy)
- session-aliases.js: validate cleanupAliases param is a function,
  check saveAliases return value, guard resolveAlias against empty input
- Sync .cursor/skills/strategic-compact/suggest-compact.sh with the
  fixed main version (CLAUDE_SESSION_ID instead of $$)

scripts/lib/utils.js

@@ -34,13 +34,6 @@ function getSessionsDir() {
   return path.join(getClaudeDir(), 'sessions');
 }
 
-/**
- * Get the session aliases file path
- */
-function getAliasesPath() {
-  return path.join(getClaudeDir(), 'session-aliases.json');
-}
-
 /**
  * Get the learned skills directory
  */
@@ -447,7 +440,6 @@ module.exports = {
   getHomeDir,
   getClaudeDir,
   getSessionsDir,
-  getAliasesPath,
   getLearnedSkillsDir,
   getTempDir,
   ensureDir,