Refactor App.tsx from god component to context-based architecture

Replace prop drilling with React context providers. App.tsx shrinks
from 427 lines to ~80 lines of pure layout. Components consume shared
state directly via 7 context providers instead of threading 50+ props.

Key changes:
- 7 context providers wrapping existing hooks (encounter, bestiary,
  player characters, side panel, theme, bulk import, initiative rolls)
- 2 coordinating hooks extracted from App.tsx (useInitiativeRolls,
  useAutoStatBlock)
- All 9 affected components refactored from prop-based to context-based
- 6 test files updated to use providers or context mocks
- Prop count enforcement script (max 8 per component interface)
- Constitution principle II-A added (context-based state flow)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.specify/memory/constitution.md

@@ -1,9 +1,9 @@
 <!--
   Sync Impact Report
   ───────────────────
-  Version change: 2.2.1 → 3.0.0 (MAJOR — specs describe features not changes, proportional workflow)
+  Version change: 3.0.0 → 3.1.0 (MINOR — new principle II-A: context-based state flow)
   Modified sections:
-    - Development Workflow: specs are living feature documents; full pipeline for new features only
+    - Core Principles: added II-A. Context-Based State Flow (max 8 props, context over prop drilling)
   Templates requiring updates: none
 -->
 # Encounter Console Constitution
@@ -38,6 +38,22 @@ dependency direction:
 
 A module in an inner layer MUST NOT import from an outer layer.
 
+### II-A. Context-Based State Flow
+
+UI components MUST consume shared application state via React context
+providers, not prop drilling. Props are reserved for per-instance
+configuration (e.g., a specific data item, a layout variant, a ref).
+
+- Components MUST NOT declare more than 8 explicit props in their
+  own interface. This is enforced by `scripts/check-component-props.mjs`
+  at pre-commit.
+- Generic UI primitives (`components/ui/`) that extend HTML element
+  attributes are exempt — only explicitly declared props count, not
+  inherited HTML attributes.
+- Coordinating hooks that consume multiple contexts (e.g.,
+  `useInitiativeRolls`) are preferred over wiring callbacks through
+  a parent component.
+
 ### III. Clarification-First
 
 Before making any non-trivial assumption during specification,
@@ -140,4 +156,4 @@ MUST comply with its principles.
 **Compliance review**: Every spec and plan MUST include a
 Constitution Check section validating adherence to all principles.
 
-**Version**: 3.0.0 | **Ratified**: 2026-03-03 | **Last Amended**: 2026-03-11
+**Version**: 3.1.0 | **Ratified**: 2026-03-03 | **Last Amended**: 2026-03-19