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/DECISIONS.md

@@ -0,0 +1,47 @@
+# DECISIONS.md — Hydrotech Beam
+
+Numbered decision log. Check here before proposing anything that contradicts a prior decision.
+
+---
+
+## DEC-HB-001: Single-objective formulation
+- **Date:** 2026-02-08
+- **By:** Technical Lead 🔧
+- **Decision:** Minimize mass as sole objective. Tip displacement (≤ 10 mm) and von Mises stress (≤ 130 MPa) as hard constraints.
+- **Rationale:** Mass is Antoine's clear priority. Displacement and stress are pass/fail limits, not competing objectives to trade off. Single-objective converges faster and is appropriate for 4 design variables.
+- **Status:** Proposed — awaiting CEO confirmation
+
+## DEC-HB-002: Two-phase optimization strategy
+- **Date:** 2026-02-08
+- **By:** Technical Lead 🔧
+- **Decision:** Phase 1 = Latin Hypercube DoE (40–50 trials) to map landscape. Phase 2 = TPE via Optuna (60–100 trials) to converge.
+- **Rationale:** DoE first catches model failures, maps feasibility, reveals sensitivities. TPE handles mixed integer/continuous natively and is sample-efficient.
+- **Status:** Proposed — awaiting CEO confirmation
+
+## DEC-HB-003: Integer handling for hole_count
+- **Date:** 2026-02-08
+- **By:** Technical Lead 🔧
+- **Decision:** Treat `hole_count` as true integer throughout (not continuous + rounding).
+- **Rationale:** Only 11 levels (5–15). NX model must rebuild with integer count anyway. TPE handles mixed types natively.
+- **Status:** Proposed — awaiting CEO confirmation
+
+## DEC-HB-004: Project structure — KB-integrated layout
+- **Date:** 2026-02-09
+- **By:** Manager 🎯 + CEO
+- **Decision:** Projects use KB-integrated structure with `models/`, `kb/`, `studies/`, `deliverables/`. Knowledge base follows accumulation principle from shared KB skill. Studies are self-contained with own model copy and introspection.
+- **Rationale:** Centralizes project knowledge, supports multiple studies per project, enables CDR compilation from KB, keeps everything in Gitea.
+- **Status:** Approved
+
+## DEC-HB-005: No Notion — Gitea + .md as source of truth
+- **Date:** 2026-02-09
+- **By:** CEO
+- **Decision:** All project documentation lives as .md files in the Atomizer Gitea repo. No external project management tools.
+- **Rationale:** CEO preference. Efficient, version-controlled, browseable on Gitea, accessible to all agents.
+- **Status:** Approved
+
+## DEC-HB-006: KB skill — extension pattern, no fork
+- **Date:** 2026-02-09
+- **By:** Manager 🎯 + CEO
+- **Decision:** Use Mario's shared knowledge-base skill as-is. Atomizer maintains an extension file (`knowledge-base-atomizer-ext.md`) for agent-specific workflows. No fork of the shared repo.
+- **Rationale:** Avoids merge conflicts, gets upstream improvements automatically, clean separation between general toolbox and Atomizer playbook.
+- **Status:** Approved