Restructure Hydrotech Beam project — KB-integrated layout

New project structure with knowledge base integration:
- kb/ with components, materials, fea, dev generations
- models/ for reference NX files (golden copies)
- studies/ for self-contained optimization campaigns
- deliverables/ for final outputs
- DECISIONS.md decision log (6 decisions tracked)
- BREAKDOWN.md (moved from 1_breakdown/)
- Gen 001 created from intake + technical breakdown

KB extension file: atomizer/shared/skills/knowledge-base-atomizer-ext.md

Refs: DEC-HB-004, DEC-HB-005, DEC-HB-006

projects/hydrotech-beam/kb/materials/steel-aisi.md

@@ -0,0 +1,26 @@
+# Steel (AISI)
+
+**Status:** Placeholder — needs full material card details
+
+---
+
+## Properties
+
+| Property | Value | Units | Source |
+|----------|-------|-------|--------|
+| Standard | AISI | — | Intake |
+| Grade | ❓ TBD | — | Need from NX model |
+| Yield strength | ❓ TBD | MPa | — |
+| E (Young's modulus) | ❓ TBD | GPa | — |
+| Density | ❓ TBD | kg/m³ | — |
+| Poisson's ratio | ❓ TBD | — | — |
+
+## Notes
+
+- Stress allowable of 130 MPa was given as constraint — need to confirm basis (Gap G9)
+- If yield is ~250 MPa, then 130 MPa implies SF ≈ 1.9 — conservative
+- Material card should be extracted from NX model during introspection
+
+## History
+
+- **Gen 001** (2026-02-09): Placeholder from intake — "Steel (AISI)" is all we have