feat: vfs - add dynamic filesystem mounts and safe unmount lifecycle

programs/src/disks/actions.cpp

@@ -150,7 +150,33 @@ void do_mount_partition() {
 
     int global_idx = part_indices[dt.selected_part];
     int driveNum = 1 + global_idx;
-    if (driveNum >= 16) driveNum = 15;
+
+    int mountedDrives[MAX_DRIVES];
+    int mountedCount = montauk::drivelist(mountedDrives, MAX_DRIVES);
+    bool occupied[MAX_DRIVES] = {};
+    for (int i = 0; i < mountedCount; i++) {
+        int mountedDrive = mountedDrives[i];
+        if (mountedDrive >= 0 && mountedDrive < MAX_DRIVES) {
+            occupied[mountedDrive] = true;
+        }
+    }
+
+    // Preserve the stable partition-to-drive mapping when it is available.
+    // Otherwise use the lowest free non-ramdisk drive in the full namespace.
+    if (driveNum >= MAX_DRIVES || occupied[driveNum]) {
+        driveNum = -1;
+        for (int candidate = 1; candidate < MAX_DRIVES; candidate++) {
+            if (!occupied[candidate]) {
+                driveNum = candidate;
+                break;
+            }
+        }
+    }
+
+    if (driveNum < 0) {
+        set_status("Mount failed (no free drive slot)");
+        return;
+    }
 
     int r = montauk::fs_mount(global_idx, driveNum);
     if (r < 0) {

programs/src/disks/disks.h

@@ -32,6 +32,8 @@ static constexpr int MAP_H        = 48;
 static constexpr int MAP_PAD      = 16;
 static constexpr int MAX_PARTS    = 32;
 static constexpr int MAX_DISKS    = 32;
+// Matches Fs::Vfs::MaxDrives; used for selecting a free mount target.
+static constexpr int MAX_DRIVES   = 64;
 static constexpr int STATUS_H     = 44;
 
 static constexpr int TB_BTN_Y     = 7;