v2.63.0: BinaryLifter: SH-2A backend (`_lift_sh2a` + `_SH2aState`).** Adds Renesas SH-2A

BinaryLifter: SH-2A backend (_lift_sh2a + _SH2aState). Adds Renesas SH-2A (SH7058/SH7059)
as the 18th ISA supported by BinaryLifter.lift_function().

New:

• _lift_sh2a(func_va, max_insns): lifts an SH-2A function to pseudo-C IR. Uses EcuSH2aDecoder
  directly (no Capstone, no subprocess). Flat ECU ROM fallback: when _sections is empty (no ELF
  header), treats func_va as a direct file offset (base_va=0). Truncates at first RETURN +
  delay-slot instruction to prevent running into zero-padded ROM space.
• _SH2aState: register-tracking state machine for SH-2A (Renesas SuperH calling convention).
  R4-R7 = arg0-arg3; R0 = return value; R15 = stack pointer. Dispatches on SH2aInsn.insn_type
  directly (no regex) — clean because EcuSH2aDecoder pre-categorizes every instruction. Handles
  LR_SAVE/LR_RESTORE (prologue comment), RETURN, CALL (direct + indirect JSR), BRANCH (conditional
  BT/BF + unconditional BRA + indirect JMP), LOAD (MOV.L/W/B with displacement), STORE, and MISC.
  Taint propagation from tainted args through call results and loads.
• Arch dispatch: sh2a, sh-2a, sh2 all dispatch to _lift_sh2a.
• 46 tests in tests/test_binary_lifter_sh2a.py.
• Docs: docs/module-reference/binary-lifter-sh2a.md.

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