feat: Stage 2 — alert dashboard with live table and stats

Adds a bubbles/table alert list showing Name, Status, Started (relative
time), and Ack By columns. Stats bar shows total/firing/resolved counts.
Filter cycles firing → resolved → all with [f]. Auto-refresh fires on
the configured interval via tea.Tick. Table scrolls with j/k.

internal/api/client.go

@@ -4,6 +4,8 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"net/url"
+	"strconv"
 	"strings"
 	"time"
 )
@@ -58,6 +60,38 @@ func (c *Client) do(req *http.Request, out any) error {
 	return nil
 }
 
+// ListAlerts fetches alerts from the server. status may be "firing", "resolved", or "" for all.
+func (c *Client) ListAlerts(status string, limit int) ([]Alert, error) {
+	q := url.Values{}
+	if status != "" {
+		q.Set("status", status)
+	}
+	if limit > 0 {
+		q.Set("limit", strconv.Itoa(limit))
+	}
+	path := "/api/alerts"
+	if len(q) > 0 {
+		path += "?" + q.Encode()
+	}
+
+	req, err := c.newRequest(http.MethodGet, path)
+	if err != nil {
+		return nil, err
+	}
+	var alerts []Alert
+	return alerts, c.do(req, &alerts)
+}
+
+// GetAlertStats fetches aggregate alert counts.
+func (c *Client) GetAlertStats() (*AlertStats, error) {
+	req, err := c.newRequest(http.MethodGet, "/api/stats/alerts")
+	if err != nil {
+		return nil, err
+	}
+	var stats AlertStats
+	return &stats, c.do(req, &stats)
+}
+
 // HealthCheck calls GET /healthz (unauthenticated path, no auth needed but we send it anyway).
 func (c *Client) HealthCheck() error {
 	req, err := http.NewRequest(http.MethodGet, c.baseURL+"/healthz", nil)