v2.66.0: BinaryLifter: SH-2A backend upgraded to CFG + structured control flow.

BinaryLifter: SH-2A backend upgraded to CFG + structured control flow.
Replaces the linear-walk lifter with a full decompiler pipeline.

Changed:

• _lift_sh2a() now builds a CFG (cfg_sh2a.build_cfg) and runs the
  dominator-based structurizer (structurizer.Structurizer) before emitting
  pseudo-C. Output is now if/while/for structured code instead of goto
  chains. Falls back to linear block-ordered emit if the structurizer raises.
• _SH2aState.emit() is unchanged — it remains the per-instruction emitter
  callback, called by the structurizer via a lambda.

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