Rename the persistent agent integration to Sybil Agent

Use SYBIL_AGENT_BASE_URL and SYBIL_AGENT_API_KEY with the renamed sybil-agent
service. Update errors, API documentation, and test fixtures while retaining the
existing room protocol and browser storage keys for compatibility.

Validation: 44 server tests, 51 web tests, and both production builds.

web/src/lib/agent-room-presentation.ts

@@ -26,7 +26,7 @@ const entryId = (message: Message): bigint | undefined => {
 const toolId = (message: Message) => typeof data(message).toolCallId === 'string' ? String(data(message).toolCallId) : message.id;
 
 /**
- * Pi sends messages and activity as separate frames. This adapter publishes them
+ * Sybil Agent sends messages and activity as separate frames. This adapter publishes them
  * as one room snapshot and latches transcript typing off when a new public reply
  * arrives. An unchanged busy frame cannot restore the old turn's indicator.
  * Actual activity remains untouched for the sidebar, workers, and queue display.

web/tests/agent-room.test.mjs

@@ -9,7 +9,7 @@ import { createAgentOptimisticOutbox } from "../src/lib/agent-optimistic-outbox.
 
 const message = (id, role = "assistant", extra = {}) => ({
   id: `entry:${id}`, createdAt: `2026-10-14T10:00:${String(id % 60).padStart(2, "0")}.000Z`,
-  role, content: `message ${id}`, name: role === "assistant" ? "Pi" : "buzzert",
+  role, content: `message ${id}`, name: role === "assistant" ? "Sybil Agent" : "buzzert",
   metadata: { kind: "message", entryId: id, status: "complete" }, ...extra,
 });
 const page = (cursor, messages = [], hasMore = false) => ({
@@ -183,7 +183,7 @@ test("malformed successful receipts keep optimistic messages retryable under the
   assert.equal(row.metadata.status, "failed");
   assert.equal(box.snapshot()[0].seenOnServer, false);
   const valid = { id: 1, status: "queued", messageId: row.id };
-  for (const malformed of [null, { error: "Invalid Pi response" }, { ...valid, id: 0 }, { ...valid, id: 1.5 },
+  for (const malformed of [null, { error: "Invalid Sybil Agent response" }, { ...valid, id: 0 }, { ...valid, id: 1.5 },
     { ...valid, id: Number.MAX_SAFE_INTEGER + 1 }, { ...valid, status: "unknown" }, { ...valid, status: ["queued"] },
     { ...valid, messageId: "inbound:sybil:other" }]) {
     response = malformed;