nx_klipper_gcode_validator.nx

nx_klipper_gcode_validator.nx -- Phase B1 of S-class hardening. Real-input validation that the substrate's emitted G-code parses as syntactically valid Klipper commands. Walks the emitted byte stream + verifies every non-comment line follows G/M/T + space- separated letter+number parameters. Per [[feedback-no-false-ok-substrate-honesty-audit]] + the S-class honest audit: emitted G-code MUST be parseable by Klipper before we send it to the Qidi. If our slicer emits something Klipper rejects mid-job, that's a half-print failure (operator's "spaghetti or where it prints halfway" failure class). This validator is the substrate-side guarantee that emitted bytes ARE valid before any filament moves. Validates: - Non-empty + non-comment lines must start with G/M/T - Command (after G/M/T) must be a decimal number - Parameters: letter (A-Z) followed by signed numeric value - No control bytes (< 0x09) outside CR/LF/TAB - F (feedrate) parameter, when present, must be positive Does NOT validate: - Command semantics (G99 wouldn't be flagged even though Klipper might reject it; substrate trusts caller's command set) - Numeric ranges (axes within build volume = simulator's job) - Klipper extended commands (SET_*, BED_MESH_*, etc.) license_tier: ORIGINAL