feat(core): event bus seed - envelope schema, durable topic log, OELBR kernel

- EventBus: dumb wire, publish/subscribe, failures surface
- Envelope: four schema planes, inject-only headers, content-addressed
- TopicLog: owned SQLite ledger, replay + by-type/time/causality
- Seed facade: durable=ledger+wire, ephemeral=wire only, fold-for-state
- Rung 1 kernel: OELBR loop, DAG plans, durable cancellation tokens
- Neuron v0 executable spec source; specs/event-bus.md citizen zero
- Standing orders: design-before-code doctrine installed

runs/rung1/main.ts

@@ -0,0 +1,58 @@
+/**
+ * Rung 1 demo executable - isolated, standalone, own universe.
+ * bun runs/rung1/main.ts
+ *
+ * Proves: DAG execution, durable pause/resume/cancel, crash-resume from
+ * fold, and the loop's transitions all landing in the ledger.
+ */
+
+import { Seed } from "../../packages/core/src/seed"
+import { runLoop, command } from "./kernel"
+
+const dbPath = process.argv[2] ?? new URL("./universe.db", import.meta.url).pathname
+
+// --- two agents, one kernel each ---
+const seed = Seed.open(dbPath)
+seed.topic({ id: "agent.worker-1.work", durability: "durable", author: "orchestrator" })
+seed.topic({ id: "agent.worker-1.control", durability: "durable", author: "system" })
+
+const worker = {
+  token: "worker-1",
+  workTopic: "agent.worker-1.work",
+  orchestrate: async () => ({
+    steps: [
+      { id: "s1", title: "survey ground", dependsOn: [] },
+      { id: "s2", title: "dig foundation", dependsOn: ["s1"] },
+      { id: "s3", title: "raise walls", dependsOn: ["s2"] },
+    ],
+  }),
+  executeStep: async (step) => {
+    console.log(`  [worker-1] executing: ${step.title}`)
+    return [{ ref: `artifacts/${step.id}.md`, kind: "output" }]
+  },
+}
+
+async function main() {
+  const mode = process.argv[2] ?? "fresh"
+  const db = mode === "resume" ? dbPath : dbPath
+
+  if (mode === "cancel-mid") {
+    // cancel between steps 1 and 2 by issuing command after first completes
+    const seedX = Seed.open(db)
+    setTimeout(() => command(seedX, "worker-1", { type: "cancel", author: "will" }), 30)
+  }
+
+  if (mode === "pause-resume") {
+    const seedX = Seed.open(db)
+    setTimeout(() => command(seedX, "worker-1", { type: "pause" }), 20)
+    setTimeout(() => command(seedX, "worker-1", { type: "resume" }), 120)
+  }
+
+  console.log(`mode=${mode}`)
+  const result = await runLoop(Seed.open(db), worker, { goal: "build the thing" })
+  console.log("status:", result.status, "| completed:", [...result.doneSteps].sort().join(","))
+  console.log("ledger:")
+  for (const e of Seed.open(db).replay("agent.worker-1.work")) console.log(`  ${e.seq}. ${e.body.type}`)
+}
+
+main()