Update SLSA generator, implement first instructions, add helper decoders

[lachlanharrisdev]

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[Copilot]

Pull Request Overview

This PR implements the first instructions for an LC-3 virtual machine and updates the SLSA security generator. The implementation adds basic instruction execution infrastructure with support for ADD, AND, NOT, and TRAP operations, replacing placeholder code with functional instruction processing.

• Updates the SLSA generator to v2.1.0 for improved security provenance
• Implements core instruction execution logic with decode helpers and trap routines
• Establishes the main execution loop to fetch and execute instructions

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
.github/workflows/slsa-generator.yml	Updates SLSA generator version for security provenance
Makefile	Adds FLAGS variable to compiler invocation
src/main.c	Implements instruction fetch/execute loop and adds cleanup handlers
include/hardware.h	Defines LC-3 instruction opcodes and switches from Phantom-18 ISA
include/instructions.h	Adds instruction decode macros and function prototypes
src/instructions.c	Implements instruction execution functions and trap routines

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