feat: add software-architecture-design command (Path B) with IEEE 101…

[grissiom]

…6/42010 fusion

Introduce the combined /speckit.v-model.software-architecture-design command that reads requirements.md directly and produces a single architecture artifact, replacing the two-step Path A chain (system-design + architecture-design).

Key deliverables:

• New command: commands/software-architecture-design.md
• New template: templates/software-architecture-design-template.md
• Domain overlays for all three regulated domains:
  • iso_26262: Full ASPICE SWE.2 BP1–BP9 process guidance + compliance checklist
  • do_178c: Stub with DAL allocation + temporal constraints
  • iec_62304: Stub with safety class allocation + defensive coding
• Setup scripts already support --require-software-architecture-design
• V-model example artifacts in specs/007-software-architecture-design/v-model/ (requirements, architecture design, acceptance plan, integration test, module design, unit test, traceability matrix)

Design decisions (from spec clarifications):

• SWE.2 is domain-gated: generated only when domain: iso_26262
• Path B ARCH elements trace strictly to REQ-NNN (never SYS-NNN)
• Path A coexistence: warn but proceed; both artifacts coexist
• IEEE 1016:2009 design entity model synthesized within IEEE 42010 views

IEEE 1016/42010 fusion:

• Logical View ← IEEE 1016 Decomposition View (§5.1) + Dependency View (§5.2)
• Interface View ← IEEE 1016 Interface Identification (§5.3) + IEEE 42010
• Data Flow View ← IEEE 1016 Data Design (§5.4) + IEEE 42010
• Process View ← IEEE 42010 / Kruchten 4+1 only (synthesis differentiator)

Documentation updates:

• docs/: v-model-overview, usage-examples, standards-reference, compliance-guide, domain-decoupling-design, id-schema-guide, v-model-config
• site/: commands reference (15 commands, Path A/B), templates reference, scripts reference, roadmap, domain-overlays guide, automotive-adas tutorial, medical-device tutorial
• All 14→15 command count references updated

Coverage: 16/16 ARCH→ITP (18 ITPs, 40 ITSs), 28/28 REQ→ATP, 13/13 MOD→UTP

Description

Brief description of what this PR does.

Related Issue: Fixes #

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Changes Made

Checklist

General

• My changes follow the project's contributing guidelines
• I have performed a self-review of my changes
• I have updated documentation (if applicable)
• I have updated the CHANGELOG.md (if applicable)

Commands (commands/*.md)

• JSON key references match actual script output (e.g., VMODEL_DIR, not v_model_dir)
• Deterministic tasks are delegated to scripts, not AI self-assessment
• Examples in the prompt use the correct ID schema

Scripts (scripts/)

• Bash and PowerShell versions produce identical output
• Category-prefixed IDs are handled correctly (REQ-NF-001, REQ-IF-001, etc.)
• JSON output mode (--json) matches documented key names
• Tested with mixed-category test data

Testing

• Extension installs with specify extension add --dev
• All 4 Bash scripts run without errors
• validate-requirement-coverage.sh correctly detects gaps for category-prefixed IDs
• build-matrix.sh generates a valid traceability matrix