feat: add Board Planning module with investment/assessment scenario modeling

Implements Phase 11 Forecasting Tools - a "what-if" scenario planning system
for HOA boards to model financial decisions before committing.

Backend:
- 3 new tenant-scoped tables: board_scenarios, scenario_investments, scenario_assessments
- Migration script (013) for existing tenants
- Full CRUD service for scenarios, investments, and assessments
- Projection engine adapted from cash flow forecast with investment/assessment deltas
- Scenario comparison endpoint (up to 4 scenarios)
- Investment execution flow: converts planned → real investment_accounts + journal entry

Frontend:
- New "Board Planning" sidebar section with 3 pages
- Investment Scenarios: list, create, detail with investments table + timeline
- Assessment Scenarios: list, create, detail with changes table
- Scenario Comparison: multi-select overlay chart + summary metrics
- Shared components: ProjectionChart, InvestmentTimeline, ScenarioCard, forms
- AI Recommendation → Investment Plan integration (Story 1A)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/src/modules/board-planning/board-planning.controller.ts

@@ -0,0 +1,130 @@
+import { Controller, Get, Post, Put, Delete, Body, Param, Query, Req, UseGuards } from '@nestjs/common';
+import { ApiTags, ApiBearerAuth } from '@nestjs/swagger';
+import { JwtAuthGuard } from '../auth/guards/jwt-auth.guard';
+import { AllowViewer } from '../../common/decorators/allow-viewer.decorator';
+import { BoardPlanningService } from './board-planning.service';
+import { BoardPlanningProjectionService } from './board-planning-projection.service';
+
+@ApiTags('board-planning')
+@Controller('board-planning')
+@ApiBearerAuth()
+@UseGuards(JwtAuthGuard)
+export class BoardPlanningController {
+  constructor(
+    private service: BoardPlanningService,
+    private projection: BoardPlanningProjectionService,
+  ) {}
+
+  // ── Scenarios ──
+
+  @Get('scenarios')
+  @AllowViewer()
+  listScenarios(@Query('type') type?: string) {
+    return this.service.listScenarios(type);
+  }
+
+  @Get('scenarios/:id')
+  @AllowViewer()
+  getScenario(@Param('id') id: string) {
+    return this.service.getScenario(id);
+  }
+
+  @Post('scenarios')
+  createScenario(@Body() dto: any, @Req() req: any) {
+    return this.service.createScenario(dto, req.user.sub);
+  }
+
+  @Put('scenarios/:id')
+  updateScenario(@Param('id') id: string, @Body() dto: any) {
+    return this.service.updateScenario(id, dto);
+  }
+
+  @Delete('scenarios/:id')
+  deleteScenario(@Param('id') id: string) {
+    return this.service.deleteScenario(id);
+  }
+
+  // ── Scenario Investments ──
+
+  @Get('scenarios/:scenarioId/investments')
+  @AllowViewer()
+  listInvestments(@Param('scenarioId') scenarioId: string) {
+    return this.service.listInvestments(scenarioId);
+  }
+
+  @Post('scenarios/:scenarioId/investments')
+  addInvestment(@Param('scenarioId') scenarioId: string, @Body() dto: any) {
+    return this.service.addInvestment(scenarioId, dto);
+  }
+
+  @Post('scenarios/:scenarioId/investments/from-recommendation')
+  addFromRecommendation(@Param('scenarioId') scenarioId: string, @Body() dto: any) {
+    return this.service.addInvestmentFromRecommendation(scenarioId, dto);
+  }
+
+  @Put('investments/:id')
+  updateInvestment(@Param('id') id: string, @Body() dto: any) {
+    return this.service.updateInvestment(id, dto);
+  }
+
+  @Delete('investments/:id')
+  removeInvestment(@Param('id') id: string) {
+    return this.service.removeInvestment(id);
+  }
+
+  // ── Scenario Assessments ──
+
+  @Get('scenarios/:scenarioId/assessments')
+  @AllowViewer()
+  listAssessments(@Param('scenarioId') scenarioId: string) {
+    return this.service.listAssessments(scenarioId);
+  }
+
+  @Post('scenarios/:scenarioId/assessments')
+  addAssessment(@Param('scenarioId') scenarioId: string, @Body() dto: any) {
+    return this.service.addAssessment(scenarioId, dto);
+  }
+
+  @Put('assessments/:id')
+  updateAssessment(@Param('id') id: string, @Body() dto: any) {
+    return this.service.updateAssessment(id, dto);
+  }
+
+  @Delete('assessments/:id')
+  removeAssessment(@Param('id') id: string) {
+    return this.service.removeAssessment(id);
+  }
+
+  // ── Projections ──
+
+  @Get('scenarios/:id/projection')
+  @AllowViewer()
+  getProjection(@Param('id') id: string) {
+    return this.projection.getProjection(id);
+  }
+
+  @Post('scenarios/:id/projection/refresh')
+  refreshProjection(@Param('id') id: string) {
+    return this.projection.computeProjection(id);
+  }
+
+  // ── Comparison ──
+
+  @Get('compare')
+  @AllowViewer()
+  compareScenarios(@Query('ids') ids: string) {
+    const scenarioIds = ids.split(',').map((s) => s.trim()).filter(Boolean);
+    return this.projection.compareScenarios(scenarioIds);
+  }
+
+  // ── Execute Investment ──
+
+  @Post('investments/:id/execute')
+  executeInvestment(
+    @Param('id') id: string,
+    @Body() dto: { executionDate: string },
+    @Req() req: any,
+  ) {
+    return this.service.executeInvestment(id, dto.executionDate, req.user.sub);
+  }
+}