tools: Preserve SPI NOR module overrides

[enjoy-digital]

Summary

• make per-device opcode corrections first-class generator inputs, with validated replace/add/remove operations
• apply explicit opcode, dummy-cycle, and quad-enable overrides after imported capabilities are interpreted
• migrate the existing manual opcode, dummy-cycle, and quad-enable corrections into override_cfg.py
• teach the module template to emit the additional attributes
• add parity tests so checked-in generated modules cannot silently drift from their overrides

This addresses the regeneration problem described in #55 without blindly combining capability flags from Linux, flashrom, and OpenOCD. Modernizing those external importers remains separate follow-up work, since current Linux often discovers capabilities dynamically through SFDP.

Tests

• pytest -q (36 passed, 198 subtests passed)
• python3 -m py_compile tools/spi_nor_config_generator/override_cfg.py tools/spi_nor_config_generator/flash_module_template.py tools/spi_nor_config_generator/spi_nor_cfg_gen.py