feat(agents): darkwing host-dev launcher + entry-point consolidation

scripts/agent.sh --host-dev delegates to scripts/agent-host-dev.sh;
agents/darkwing/launch.sh provides the native development TUI
(context, skills, coding tools, /goal). Root SOUL.md is the M14-era
default-collaborator persona captured by the ACT-1 context work.
Launcher regression checks pass (test-darkwing-launch.mjs).

agents/darkwing/validate-sessions.mjs

@@ -0,0 +1,21 @@
+// Refuse damaged history before Pi's --continue can silently skip it.
+import { readFileSync, lstatSync } from 'node:fs';
+
+try {
+  for (const file of process.argv.slice(2)) {
+    if (!lstatSync(file).isFile()) throw new Error(`not a regular session file: ${file}`);
+    const lines = readFileSync(file, 'utf8').trim().split('\n');
+    const entries = lines.map((line) => JSON.parse(line));
+    const header = entries[0];
+    if (header?.type !== 'session' || typeof header.id !== 'string' || !header.id ||
+        typeof header.version !== 'number' || typeof header.cwd !== 'string' ||
+        !Number.isFinite(Date.parse(header.timestamp)) ||
+        entries.slice(1).some((entry) => !entry || typeof entry.type !== 'string')) {
+      throw new Error(`invalid session structure: ${file}`);
+    }
+    if (header.cwd !== process.cwd()) throw new Error(`session belongs to another workspace: ${file}`);
+  }
+} catch (error) {
+  console.error(`darkwing: cannot safely resume: ${error.message}; inspect history or explicitly use --fresh`);
+  process.exit(1);
+}