Reclaim Windows space for Linux: remove dual boot or retain a minimal Windows installation #121

Feature request

Add a guided workflow to reclaim Windows space for an existing Linux installation, with two explicit choices:

1. Remove Windows and stop dual booting.
2. Keep a minimal, usable Windows installation and allocate the remaining reclaimable space to Linux.

The destination should be the existing Linux root filesystem, rather than only a new data partition. The immediate need is enough root space for Omarchy updates and applications.

Concrete use case

A roughly 2 TB NVMe has an approximately 196 GiB Omarchy root at 97% usage, about 1.21 TiB already unallocated, and around 412 GiB allocated to Windows. The free regions are separated from the LUKS/Btrfs Linux root by other partitions. The user wants to preserve the Linux installation and either remove Windows or retain it with a much smaller allocation.

Requested experience

• Show the physical partition layout alongside filesystem usage, including unallocated regions and whether they are adjacent to Linux.
• Offer explicit Remove Windows and Keep Windows with reduced space choices. Determine feasible Windows sizing from actual usage and filesystem constraints rather than an arbitrary fixed minimum.
• Preview the resulting layout and Linux root capacity, identifying every affected partition before any destructive operation.
• Account for NTFS state, encryption, shared EFI/boot dependencies and recovery partitions; do not identify disposable partitions solely from their position or filesystem type.
• Explain whether the chosen plan can run in the current session or requires a live USB for moving or unmounting partitions.
• Coordinate with an appropriate partition editor/backend for changes to the partition, LUKS mapping and Btrfs filesystem. Preserve Linux bootability and Windows bootability when Windows is retained.
• Keep destructive operations behind explicit confirmation, provide backup guidance, and refresh the measured capacity afterward. SSH sources should remain read-only.

Relationship to the resizing PR

#120 adds a local GParted handoff for growing or shrinking a partition. This request goes further: discover reclaimable Windows space, explain migration options and constraints, and guide the complete transition to a larger Linux root. Opening GParted alone does not perform that migration.

The Omarchy side needs a supported encrypted-root migration procedure and boot integration. In particular, adding an independent encrypted Btrfs root member must not introduce an early-boot dependency that prevents the next boot; related report: omacom/omarchy#10029.

No partitions have been changed as part of this request.

Companion Omarchy request: omacom/omarchy#17032