feat(sd): add progress feedback for SD card format operation

[cptkoolbeenz]

Problem

The SYST:STOR:SD:FORMat command provides no feedback during execution. SD card formatting can take significant time (especially for large cards), leaving users uncertain whether:

• The operation is still in progress
• The device has hung
• The format completed successfully

Proposed Solutions

Option A: Status Query Command (Recommended)

Add SYST:STOR:SD:FORMat? query command that returns format status:

SYST:STOR:SD:FORMat?

Returns:

• 0 - No format in progress (idle)
• 1 - Format currently in progress
• 2 - Format completed successfully (could auto-clear after query)
• -1 - Format failed (error)

Pros:

• SCPI-compliant (query form of existing command)
• Non-blocking - user can poll as frequently as desired
• Works well with automation/scripting

Option B: Progress Percentage

If the underlying filesystem library provides progress callbacks:

SYST:STOR:SD:FORMat?

Returns: 0-100 representing percentage complete, or -1 for error

Note: May not be feasible depending on SYS_FS_DriveFormat() implementation.

Option C: Periodic Progress Output

Return progress indicators (. or percentage) during format:

SYST:STOR:SD:FORMat
..........  (10%)
..........  (20%)
...
OK

Cons:

• May interfere with SCPI parsers expecting clean responses
• Harder to parse programmatically

Implementation Notes

1. Add state tracking variable for format operation:

   typedef enum {
       SD_FORMAT_IDLE = 0,
       SD_FORMAT_IN_PROGRESS = 1,
       SD_FORMAT_COMPLETE = 2,
       SD_FORMAT_ERROR = -1
   } sd_format_status_t;

2. The format operation already runs in the SD card task state machine, so adding status tracking should be straightforward.

3. Consider timeout - if format takes >5 minutes, should it be considered failed?

Acceptance Criteria

• User can query format status while operation is in progress
• User can distinguish between "not started", "in progress", and "complete"
• Errors are reported appropriately
• Works correctly when queried from USB CDC or WiFi

Related

• Current format implementation: sd_card_manager.c:SD_CARD_MANAGER_PROCESS_STATE_FORMAT
• SCPI interface: SCPIStorageSD.c