feat: investment scenario UX improvements and interest calculations

- Refresh Recommendations now shows inline processing banner with
  animated progress bar while keeping existing results visible (dimmed).
  Auto-scrolls to AI section and shows titled notification on completion.
- Investment recommendations now auto-calculate purchase and maturity
  dates from a configurable start date (defaults to today) in the
  "Add to Plan" modal, so scenarios build projections immediately.
- Projection engine computes per-investment and total interest earned,
  ROI percentage, and total principal invested. Summary cards on the
  Investment Scenario detail page display these metrics prominently.
- Replaced dropdown action menu with inline Edit/Execute/Remove
  icon buttons matching the assessment scenarios pattern.

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

backend/src/modules/board-planning/board-planning-projection.service.ts

@@ -49,6 +49,8 @@ export class BoardPlanningProjectionService {
     // ── 2. Build month-by-month projection ──
     let { opCash, resCash, opInv, resInv } = baseline.openingBalances;
     const datapoints: any[] = [];
+    let totalInterestEarned = 0;
+    const interestByInvestment: Record<string, number> = {};
 
     for (let i = 0; i < months; i++) {
       const year = startYear + Math.floor(i / 12);
@@ -65,6 +67,10 @@ export class BoardPlanningProjectionService {
 
       // Scenario investment deltas for this month
       const invDelta = this.computeInvestmentDelta(investments, year, month);
+      totalInterestEarned += invDelta.interestEarned;
+      for (const [invId, amt] of Object.entries(invDelta.interestByInvestment)) {
+        interestByInvestment[invId] = (interestByInvestment[invId] || 0) + amt;
+      }
 
       // Scenario assessment deltas for this month
       const asmtDelta = this.computeAssessmentDelta(assessments, baseline.assessmentGroups, year, month);
@@ -113,7 +119,7 @@ export class BoardPlanningProjectionService {
     }
 
     // ── 3. Summary metrics ──
-    const summary = this.computeSummary(datapoints, baseline, assessments);
+    const summary = this.computeSummary(datapoints, baseline, assessments, investments, totalInterestEarned, interestByInvestment);
 
     const result = { datapoints, summary };
 
@@ -363,6 +369,8 @@ export class BoardPlanningProjectionService {
     let resCashFlow = 0;
     let opInvChange = 0;
     let resInvChange = 0;
+    let interestEarned = 0;
+    const interestByInvestment: Record<string, number> = {};
 
     for (const inv of investments) {
       if (inv.executed_investment_id) continue; // skip already-executed investments
@@ -386,8 +394,11 @@ export class BoardPlanningProjectionService {
         if (md.getFullYear() === year && md.getMonth() + 1 === month) {
           const purchaseDate = inv.purchase_date ? new Date(inv.purchase_date) : new Date();
           const daysHeld = Math.max((md.getTime() - purchaseDate.getTime()) / 86400000, 1);
-          const interestEarned = principal * (rate / 100) * (daysHeld / 365);
-          const maturityTotal = principal + interestEarned;
+          const invInterest = principal * (rate / 100) * (daysHeld / 365);
+          const maturityTotal = principal + invInterest;
+
+          interestEarned += invInterest;
+          interestByInvestment[inv.id] = (interestByInvestment[inv.id] || 0) + invInterest;
 
           if (isOp) { opCashFlow += maturityTotal; opInvChange -= principal; }
           else { resCashFlow += maturityTotal; resInvChange -= principal; }
@@ -401,7 +412,7 @@ export class BoardPlanningProjectionService {
       }
     }
 
-    return { opCashFlow, resCashFlow, opInvChange, resInvChange };
+    return { opCashFlow, resCashFlow, opInvChange, resInvChange, interestEarned, interestByInvestment };
   }
 
   /** Compute assessment income delta for a given month from scenario assessment changes. */
@@ -471,7 +482,10 @@ export class BoardPlanningProjectionService {
     return { operating, reserve };
   }
 
-  private computeSummary(datapoints: any[], baseline: any, scenarioAssessments: any[]) {
+  private computeSummary(
+    datapoints: any[], baseline: any, scenarioAssessments: any[],
+    investments?: any[], totalInterestEarned = 0, interestByInvestment: Record<string, number> = {},
+  ) {
     if (!datapoints.length) return {};
 
     const last = datapoints[datapoints.length - 1];
@@ -496,13 +510,23 @@ export class BoardPlanningProjectionService {
       ? (last.reserve_cash + last.reserve_investments) / avgMonthlyReserveExpenditure
       : 0; // No planned projects = show 0 (N/A)
 
-    // Estimate total investment income from scenario investments
-    const totalInterestEarned = datapoints.reduce((sum, d, i) => {
-      if (i === 0) return 0;
-      const prev = datapoints[i - 1];
-      // Rough: increase in total that isn't from assessment/budget
-      return sum;
-    }, 0);
+    // Calculate total principal from scenario investments
+    let totalPrincipal = 0;
+    const investmentInterestDetails: Array<{ id: string; label: string; principal: number; interest: number }> = [];
+    if (investments) {
+      for (const inv of investments) {
+        if (inv.executed_investment_id) continue;
+        const principal = parseFloat(inv.principal) || 0;
+        totalPrincipal += principal;
+        const interest = interestByInvestment[inv.id] || 0;
+        investmentInterestDetails.push({
+          id: inv.id,
+          label: inv.label,
+          principal: round2(principal),
+          interest: round2(interest),
+        });
+      }
+    }
 
     return {
       end_liquidity: round2(endLiquidity),
@@ -513,6 +537,10 @@ export class BoardPlanningProjectionService {
       end_operating_investments: last.operating_investments,
       end_reserve_investments: last.reserve_investments,
       period_change: round2(endLiquidity - allLiquidity[0]),
+      total_interest_earned: round2(totalInterestEarned),
+      total_principal_invested: round2(totalPrincipal),
+      roi_percentage: totalPrincipal > 0 ? round2((totalInterestEarned / totalPrincipal) * 100) : 0,
+      investment_interest_details: investmentInterestDetails,
     };
   }
 }