Stability conditions

The Bridgeland refinement of weak stability, together with phase analysis, symmetry actions, metric geometry, support properties, numerical walls, and abstract family interfaces. Weak stability is the child Weak/, which this umbrella imports; ordinary prestability and stability conditions carry their weak parent structurally. Declaration namespaces remain CategoryTheory.Triangulated.WeakStabilityCondition.StabilityCondition; a namespace cutover would invalidate the immutable review payloads that exe/RestateHistoricalNames.lean protects.