v2.59.0: EcuSH2aDecoder: Renesas SH-2A decoder for Honda/Subaru ECU firmware.** Pure-Pyth

EcuSH2aDecoder: Renesas SH-2A decoder for Honda/Subaru ECU firmware. Pure-Python decoder
for the SH-2A ISA (Renesas SH7058/SH7059). Capstone 5.0.7 has no SH-2A support; this module
closes the gap and enables BinaryContext, WindowAnalyzer, and manual RE on Honda CBR250RR and
Subaru (SH7058S, EcuFlash corpus) ECU ROMs.

• EcuSH2aDecoder: disassemble(), decode_one(), function_starts(), insn_length()
• SH2aInsn: offset, is_32bit, mnemonic, insn_type, raw, target, rd, rs, imm
• insn_type: RETURN, BRANCH, CALL, LR_SAVE, LR_RESTORE, LOAD, STORE, MISC
• 32-bit SH-2A discrimination: four 0xF00F masks per Renesas SH2A HW Manual Rev.2.00; MOWI20 uses 0xF00F == 0x0005 (not 0xF0FF) because imm[19:16] occupies bits[7:4] and varies
• function_starts() primary: STS.L PR, @-R15 (0x4F22); secondary: STS PR, Rn leaf prologue with preceding-STS.L suppression
• Branch targets include SH-2 delay slot: target = VA + 4 + disp * 2
• PC-relative load: (VA + 4 & ~3) + disp * 4 (4-byte aligned PC)
• from_path() / from_bytes() convenience wrappers; FileNotFoundError wrapped with context
• 69 tests; FORGE gate: PASSED (0 findings)

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