feat: per-BU trend lines in counts history chart

- Create ivanti_counts_history_by_bu table (bu_ownership, state, count per sync)
- Sync writes per-BU snapshot alongside global history on each sync
- Seed table with current counts for immediate first data point
- GET /counts/history accepts ?teams param — queries per-BU table when filtered
- IvantiCountsChart accepts teamsParam prop, re-fetches on scope change
- ReportingPage passes getActiveTeamsParam() to the chart
- Historical per-BU data accumulates from this point forward
- Global history (no filter) still uses the original aggregate table

backend/routes/ivantiFindings.js

@@ -529,6 +529,19 @@ async function syncClosedCount(openCount, apiKey, clientId, skipTls) {
                 `INSERT INTO ivanti_counts_history (open_count, closed_count) VALUES ($1, $2)`,
                 [openCount, closedCount]
             );
+
+            // Per-BU history snapshot — enables scoped trend lines
+            try {
+                await pool.query(`
+                    INSERT INTO ivanti_counts_history_by_bu (bu_ownership, state, count)
+                    SELECT bu_ownership, state, COUNT(*)
+                    FROM ivanti_findings
+                    WHERE bu_ownership != ''
+                    GROUP BY bu_ownership, state
+                `);
+            } catch (err) {
+                console.error('[Ivanti Findings] Per-BU history snapshot failed (non-fatal):', err.message);
+            }
         }
 
         console.log(`[Ivanti Findings] Counts updated — open: ${openCount}, closed: ${closedCount}${skipHistory ? ' (history write skipped — drift guard)' : ''}`);
@@ -1146,12 +1159,45 @@ function createIvantiFindingsRouter(db, requireAuth) {
      * GET /api/ivanti/findings/counts/history
      *
      * Return the last snapshot per day (ascending) for the trend chart.
+     * Accepts optional `teams` query parameter to scope the trend to specific BUs.
+     * When teams is provided, uses the per-BU history table.
+     * When no teams, returns the global aggregate history.
      *
+     * @query {string} [teams] - Comma-separated team names (e.g. 'STEAM,ACCESS-ENG')
      * @returns {Object} 200 - { history: Array<{ date: string, open_count: number, closed_count: number }> }
      * @returns {Object} 500 - { error: string } on database error
      */
     router.get('/counts/history', async (req, res) => {
         try {
+            const teamsParam = req.query.teams;
+
+            if (teamsParam) {
+                // Per-BU history — filter and aggregate by selected teams
+                const teams = teamsParam.split(',').map(t => t.trim()).filter(Boolean);
+                if (teams.length > 0) {
+                    const patterns = teams.map(t => `%${t}%`);
+                    const { rows } = await pool.query(
+                        `SELECT date,
+                                SUM(CASE WHEN state = 'open' THEN count ELSE 0 END)::int AS open_count,
+                                SUM(CASE WHEN state = 'closed' THEN count ELSE 0 END)::int AS closed_count
+                         FROM (
+                             SELECT recorded_at::date AS date, bu_ownership, state, count,
+                                    ROW_NUMBER() OVER (
+                                        PARTITION BY recorded_at::date, bu_ownership, state
+                                        ORDER BY recorded_at DESC
+                                    ) AS rn
+                             FROM ivanti_counts_history_by_bu
+                             WHERE bu_ownership ILIKE ANY($1::text[])
+                         ) sub WHERE rn = 1
+                         GROUP BY date
+                         ORDER BY date ASC`,
+                        [patterns]
+                    );
+                    return res.json({ history: rows });
+                }
+            }
+
+            // Global history (no filter)
             const { rows } = await pool.query(
                 `SELECT date, open_count, closed_count FROM (
                      SELECT recorded_at::date AS date,