feat: Optimize context hook file listings to save tokens

Improvements to SessionStart context hook file display:

1. **Remove redundant files**: Files in "Modified" list are now excluded from "Read" list
   - Prevents duplication when a file was both read and modified
   - Reduces token usage by eliminating redundant information

2. **Use relative paths**: Convert absolute paths to project-relative paths
   - Example: /Users/alexnewman/Scripts/claude-mem/src/hooks/context.ts → src/hooks/context.ts
   - Significantly reduces token consumption in context injection
   - Makes file references more readable and portable

Implementation:
- Added toRelativePath() helper function to convert paths
- Added filesModifiedSet.forEach(file => filesReadSet.delete(file)) to remove duplicates
- Applied to both files_read and files_modified when building Sets

Impact: Reduces token usage in Tier 1 summaries (most recent session) where file lists are displayed.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/hooks/context.ts

@@ -181,12 +181,25 @@ export function contextHook(input?: SessionStartInput, useColors: boolean = fals
         const filesReadSet = new Set<string>();
         const filesModifiedSet = new Set<string>();
 
+        // Helper function to convert absolute paths to relative paths
+        const toRelativePath = (filePath: string): string => {
+          try {
+            // Only convert if it's an absolute path
+            if (path.isAbsolute(filePath)) {
+              return path.relative(cwd, filePath);
+            }
+            return filePath;
+          } catch {
+            return filePath;
+          }
+        };
+
         for (const obs of observations) {
           if (obs.files_read) {
             try {
               const files = JSON.parse(obs.files_read);
               if (Array.isArray(files)) {
-                files.forEach(f => filesReadSet.add(f));
+                files.forEach(f => filesReadSet.add(toRelativePath(f)));
               }
             } catch {
               // Skip invalid JSON
@@ -197,7 +210,7 @@ export function contextHook(input?: SessionStartInput, useColors: boolean = fals
             try {
               const files = JSON.parse(obs.files_modified);
               if (Array.isArray(files)) {
-                files.forEach(f => filesModifiedSet.add(f));
+                files.forEach(f => filesModifiedSet.add(toRelativePath(f)));
               }
             } catch {
               // Skip invalid JSON
@@ -205,6 +218,9 @@ export function contextHook(input?: SessionStartInput, useColors: boolean = fals
           }
         }
 
+        // Remove files from filesReadSet if they're already in filesModifiedSet (avoid redundancy)
+        filesModifiedSet.forEach(file => filesReadSet.delete(file));
+
         if (filesReadSet.size > 0) {
           if (useColors) {
             output.push(`${colors.dim}Files Read: ${Array.from(filesReadSet).join(', ')}${colors.reset}`);