v0.21.0 — MagicGrid methodology support

MagicGrid (Morkevičius/Aleksandravičienė) MBSE support as a pure opt-in overlay on the SysMLv2 model: MagicGrid data rides on custom_fields: with an mg_ prefix, and all MagicGrid validation is gated behind a [profiles.magicgrid] profile — non-MagicGrid models are unaffected.

Highlights

• Grid + report — mg_cell classification (MG020/021); magicgrid command renders the B/W/S × Requirements/Behavior/Structure/Parameters grid and identifies the System of Interest.
• Traceability — refines: on use cases and ActionDef/StateDef (E316/W307/refinedBy).
• System Context — gate-validated actors: (MG010–013), mg_external boundary, mg_soi System-of-Interest marker (MG060–062).
• Measures — MoEs (mg_moe, MG030–033) and MoPs (mg_mop, MG050–052) with a mopRefinedBy index.
• Solution architecture — mg_layer logical/physical (MG040–042) + matrix --allocations.
• Trade study — trade-study scores/ranks Configurations against the MoEs; mg_variant configs are parametric variants that may omit featureModel: (MG070).
• DX — corrective hint when a cross-reference wrongly includes the model-root package name (XREF-006).

Requirements REQ-TRS-MG-001…011 + REQ-TRS-XREF-006, verified by TC-TRS-MG-001…011 + TC-TRS-XREF-006 (qual suite 178/178). A complete worked example lives in model_mg/ (EV DC fast-charging station). See docs/model-guide/magicgrid.md.