Fix browser crash: limit schema context + cap table rows at 200

- Schema context limited to 7 core staffing tables (was all 12+)
- Results table capped at 200 rows to prevent DOM explosion
- Shows "first 200 of N rows" when truncated

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

crates/ui/src/main.rs

@@ -109,10 +109,12 @@ async fn fetch_health(path: &str) -> Result<String, String> {
     resp.text().await.map_err(|e| e.to_string())
 }
 
-/// Get schema context for all datasets (used for AI SQL generation)
+/// Get schema context for datasets (used for AI SQL generation).
+/// Limits to core tables to keep prompt size reasonable.
 async fn get_schema_context(datasets: &[Dataset]) -> String {
+    let core_tables = ["candidates", "clients", "job_orders", "placements", "timesheets", "call_log", "email_log"];
     let mut ctx = String::from("DATABASE SCHEMA:\n\n");
-    for ds in datasets {
+    for ds in datasets.iter().filter(|d| core_tables.contains(&d.name.as_str())) {
         let desc = run_sql(&format!("DESCRIBE {}", ds.name)).await;
         match desc {
             Ok(resp) => {
@@ -1001,6 +1003,9 @@ fn ResultsTable(response: QueryResponse) -> Element {
         if response.row_count == 0 {
             div { class: "empty-sm", "no rows returned" }
         } else if let Some(rows) = rows {
+            if rows.len() > 200 {
+                div { class: "results-info", "Showing first 200 of {response.row_count} rows" }
+            }
             div { class: "table-wrap",
                 table {
                     thead {
@@ -1011,7 +1016,7 @@ fn ResultsTable(response: QueryResponse) -> Element {
                         }
                     }
                     tbody {
-                        for row in rows.iter() {
+                        for row in rows.iter().take(200) {
                             tr {
                                 for col in response.columns.iter() {
                                     td { {format_cell(row.get(&col.name))} }