feat: add session-configurable snapshot settings via browser_configure_snapshots

Implements dynamic snapshot configuration that MCP clients can control during
sessions without requiring server restarts or CLI changes.

New tool: browser_configure_snapshots
- Configure includeSnapshots, maxSnapshotTokens, differentialSnapshots at runtime
- Changes take effect immediately for subsequent tool calls
- Shows current settings when called with no parameters
- Provides helpful tips and usage guidance

Key improvements:
1. **Runtime Configuration**: Update snapshot behavior during active sessions
2. **Client Control**: MCP clients can adapt to different workflows dynamically
3. **Immediate Effect**: No server restart required - changes apply instantly
4. **State Tracking**: Context maintains current session configuration
5. **User Friendly**: Clear feedback on current settings and changes

Updated tool descriptions:
- All interactive tools now mention "configurable via browser_configure_snapshots"
- Removed references to CLI-only configuration
- Enhanced browser_snapshot description for explicit snapshots

Benefits for users:
🔄 Dynamic configuration without restarts
🎛️ Client-controlled snapshot behavior
📊 View current settings anytime
⚡ Instant configuration changes
🎯 Adapt settings per workflow/task

Example usage:
```json
{
  "includeSnapshots": false,
  "maxSnapshotTokens": 25000,
  "differentialSnapshots": true
}
```

This transforms snapshot configuration from static CLI options into a flexible
session management system that adapts to client needs in real-time.

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

src/context.ts

@@ -636,4 +636,28 @@ export class Context {
     this._lastSnapshotFingerprint = undefined;
     this._lastPageState = undefined;
   }
+
+  updateSnapshotConfig(updates: {
+    includeSnapshots?: boolean;
+    maxSnapshotTokens?: number;
+    differentialSnapshots?: boolean;
+  }): void {
+    // Update configuration at runtime
+    if (updates.includeSnapshots !== undefined)
+      (this.config as any).includeSnapshots = updates.includeSnapshots;
+
+
+    if (updates.maxSnapshotTokens !== undefined)
+      (this.config as any).maxSnapshotTokens = updates.maxSnapshotTokens;
+
+
+    if (updates.differentialSnapshots !== undefined) {
+      (this.config as any).differentialSnapshots = updates.differentialSnapshots;
+
+      // Reset differential state when toggling
+      if (updates.differentialSnapshots)
+        this.resetDifferentialSnapshot();
+
+    }
+  }
 }