Add 397,811 recipe-motif combinations with validated simulator export

[jordanlegare]

The repository has 59 catalog-established component recipes but no exhaustive way to compose their motifs into simulator inputs. This adds a compact index covering every eligible set of two to six distinct components within the existing six-precursor/twelve-exposure limits.

• 397,811 component sets represent 48,534,764 component orders; every order is exportable on demand.
• Deterministic enumeration, source IDs/references/hashes, compressed index integrity checks, and validated recipe export.
• Six ready-to-run examples cover oxides, nitrides, sulfides, mixed families, doped oxide, and the twelve-exposure boundary.
• Combined sequences remain conceptual simulation candidates. Existing source labels are inherited, not independently re-audited; no claim that these are experimentally established stacks. The compatibility graph receives no generated evidence.
• One motif per component is composed; original whole-recipe repeat counts and physical layer ratios are not transferred.

Validation: 31 targeted tests passed across combination enumeration/export, compound catalog, sequential controller, hardened preflight, real compatibility catalog, and material ranking. Both catalog checks passed. All six examples simulated without faults. Independent code review found no important actionable issues. The uploaded Git tree matches the locally tested tree exactly.

See recipes/combinations/README.md for coverage counts and rebuild/export commands.