feat(run-page): tick the run-duration timer between SSE pushes

Adds a 1s client-side ticker that rewrites .run-duration text from a
data-started-at attribute, so the header timer on /runs/{id}
increments every second while the run is active. When an SSE swap
lands a fresh header the new server-rendered value seamlessly takes
over; when the run goes terminal the template drops the attribute
and the ticker silently skips the node, leaving the final elapsed in
place.

Other templ_*.go churn is cosmetic — regenerator versions differ
between CI and local and only the filename field in templ.Error
callsites changed.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/web/templates/run_detail.templ

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"time"
 
 	"vetting/internal/model"
 	"vetting/internal/store"
@@ -84,7 +85,12 @@ templ RunHeader(d RunPageData) {
 			<h1 class="run-header-name">{ fmt.Sprintf("Run #%d", d.Run.ID) }</h1>
 			<span class={ "run-status-badge", "run-status-" + tileMood(&d.Run) }>{ tileStatus(&d.Run) }</span>
 			<span class={ "run-profile-chip", "run-profile-" + profileChipValue(d.Run.Profile) }>{ profileChipValue(d.Run.Profile) }</span>
-			<span class="run-duration">{ runDuration(&d.Run) }</span>
+			<span
+				class="run-duration"
+				if !d.Run.State.IsTerminal() && !d.Run.StartedAt.IsZero() {
+					data-started-at={ d.Run.StartedAt.UTC().Format(time.RFC3339Nano) }
+				}
+			>{ runDuration(&d.Run) }</span>
 			if d.Run.FailedStage != "" {
 				<span class="run-failed-stage">failed at <strong>{ d.Run.FailedStage }</strong></span>
 			}