✨ feat: collapsible flash sub-steps UI + erase_all checkbox

Rename erase_before_program → erase_all (semantics fix):
- erase_all: true  → -erase_all -erase_only (entire flash chip)
- erase_all: false → -erase_only (sectors matching BIN size)
Both options always erase; the checkbox controls scope, not yes/no.

UI additions:
- SubStepFrame widget: collapsible Erase/Program/Verify sub-steps
  with status dots (○/◉/●) and colored labels
- Automatically expands on Step 2 start, collapses on completion
- Phase and progress driven by real-time program_flash output parsing
- Checkbox label: '整片Flash擦除 (Erase entire flash)'

subprocess_utils.py phase detection:
- Parses 'Performing Erase/Program/Verify Operation' for phase transitions
- Emits 'phase' callbacks (erase/program/verify/done)
- Progress % tracked within current phase

src/flash_programmer.py

@@ -98,11 +98,11 @@ def wipe_flash(
     config: Config,
     callback: ProgressCallback = None,
 ) -> FlashResult:
-    """Erase QSPI flash sectors matching the bootloader image size.
+    """Erase QSPI flash before programming.
 
-    Uses -erase_only to erase only the sectors covered by the BIN file.
-    Avoids -erase_all which fails on some flash chips (e.g. s25fl256s1)
-    that don't report memory density information.
+    Uses config.erase_all to determine erase scope:
+    - True:  -erase_all -erase_only (erase entire chip, may fail on some)
+    - False: -erase_only (erase only sectors matching the BIN file, safer)
 
     Args:
         config: Application configuration (needs fsbl_elf_path).
@@ -131,7 +131,10 @@ def wipe_flash(
         callback("start", "Erasing QSPI flash...")
 
     cmd = _build_program_flash_cmd_base(flash_tool, config)
-    cmd += ["-erase_only"]  # Erase sectors matching the BIN size (safer than -erase_all)
+    if getattr(config, 'erase_all', False):
+        cmd += ["-erase_all", "-erase_only"]  # Full chip erase
+    else:
+        cmd += ["-erase_only"]  # Erase sectors matching BIN size
 
     try:
         result = _run_command(cmd, timeout=config.step_timeouts.get("flash_erase", 120), callback=callback)
@@ -279,11 +282,11 @@ def full_flash_program(
     bin_path: str | Path,
     callback: ProgressCallback = None,
 ) -> list[FlashResult]:
-    """Execute full flash workflow: (optional wipe) → program → verify.
+    """Execute full flash workflow: wipe → program → verify.
 
-    If config.erase_before_program is True, erases flash sectors before
-    programming. Otherwise, program_flash handles sector erase during
-    programming (per-sector, not full chip).
+    Erase scope is controlled by config.erase_all:
+    - True: entire flash chip (uses -erase_all)
+    - False: sectors matching BIN file size (uses -erase_only)
 
     Args:
         config: Application configuration.
@@ -295,17 +298,10 @@ def full_flash_program(
     """
     results: list[FlashResult] = []
 
-    # Step 1: Erase (optional — controlled by config.erase_before_program)
-    if getattr(config, 'erase_before_program', True):
-        results.append(wipe_flash(config, callback))
-        if not results[-1].success:
-            return results
-    else:
-        results.append(FlashResult(
-            step="wipe",
-            success=True,
-            message="Erase skipped (handled by program_flash)",
-        ))
+    # Step 1: Erase (scope determined by config.erase_all)
+    results.append(wipe_flash(config, callback))
+    if not results[-1].success:
+        return results
 
     # Step 2: Program and verify (program_flash -verify)
     results.append(program_flash_bin(config, bin_path, callback))