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 $$)

.cursor/skills/strategic-compact/suggest-compact.sh

@@ -28,7 +28,9 @@
 # - Plan has been finalized
 
 # Track tool call count (increment in a temp file)
-COUNTER_FILE="/tmp/claude-tool-count-$$"
+# Use CLAUDE_SESSION_ID for session-specific counter (not $$ which changes per invocation)
+SESSION_ID="${CLAUDE_SESSION_ID:-${PPID:-default}}"
+COUNTER_FILE="/tmp/claude-tool-count-${SESSION_ID}"
 THRESHOLD=${COMPACT_THRESHOLD:-50}
 
 # Initialize or increment counter