fix: generate structured fail tests and fix broken -march generation

- normalize extension tokens, extract dependencies from definedBy, and
  carry them into each instruction group
- replace ad-hoc fail lists with structured error cases, reason tags
- emit annotated pass and no-alias dumps from a single primary example
  selection per instruction

Signed-off-by: Animesh Agarwal <[email protected]>

Author: AnimeshAgarwal28