Defer server file changes until guarded restart activation

Persist beta, promotion, drift, and rollback payloads until occupancy and restart-capacity checks pass. Preserve rollback snapshots and campaign ordering, and allow held rollback campaigns to resume safely.

Fixes #28

Validation: 805 tests passed, Svelte checks clean, production build passed.

src/routes/api/campaigns/[id]/+server.ts

@@ -17,7 +17,8 @@ export async function GET({ params }: { params: { id: string } }) {
         .prepare(
             `SELECT id, server, verb, rel_path, sha256_before, sha256_after,
                     LENGTH(content_before) AS size_before,
-                    LENGTH(content_after)  AS size_after
+                    LENGTH(content_after)  AS size_after,
+                    COALESCE((SELECT state FROM staged_file_changes WHERE deployment_file_id = deployment_files.id), 'applied') AS apply_state
              FROM deployment_files
              WHERE deployment_id = ?
              ORDER BY server, rel_path`

src/routes/api/campaigns/[id]/resume/+server.ts

@@ -0,0 +1,25 @@
+import { json } from '@sveltejs/kit';
+import { db } from '$lib/server/db/index.js';
+import { releaseRestartRequest } from '$lib/server/provisioning/index.js';
+import { kick } from '$lib/server/pipeline/worker.js';
+
+export function POST({ params }: { params: { id: string } }) {
+    const changed = db().transaction(() => {
+        const rows = db().prepare(`SELECT ds.server, d.state FROM deployment_servers ds
+            LEFT JOIN server_deployments d ON d.id = ds.provisioning_id
+            WHERE ds.deployment_id = ? AND ds.server_deleted_at IS NULL AND ds.restart_state IN ('held','manual')`)
+            .all(params.id) as { server: string; state: string | null }[];
+        for (const row of rows) {
+            if (row.state && ['failed','interrupted','cancelled'].includes(row.state)) {
+                releaseRestartRequest(row.server, { kind: 'campaign', id: params.id });
+            }
+        }
+        const result = db().prepare(`UPDATE deployment_servers SET restart_state = 'pending', error = NULL
+            WHERE deployment_id = ? AND server_deleted_at IS NULL AND restart_state IN ('held','manual')`).run(params.id);
+        if (result.changes) db().prepare('UPDATE deployments SET finished_at = NULL WHERE id = ?').run(params.id);
+        return result.changes;
+    })();
+    if (!changed) return json({ error: 'This campaign has no held changes to resume.' }, { status: 409 });
+    void kick().catch(err => console.error('[campaign] activation kick failed:', err));
+    return json({ ok: true }, { status: 202 });
+}