refactor: wave 2 - split atlas, auto-update-checker, session-recovery, todo-enforcer, background-task hooks

- Extract atlas/ into 15 focused modules (hook, event handler, tool policies, types, etc.)
- Split auto-update-checker into checker/ and hook/ subdirectories with single-purpose files
- Decompose session-recovery into separate recovery strategy files per error type
- Extract todo-continuation-enforcer from monolith to directory with dedicated modules
- Split background-task/tools.ts into individual tool creator files
- Extract command-executor, tmux-utils into focused sub-modules
- Split config/schema.ts into domain-specific schema files
- Decompose cli/config-manager.ts into focused modules
- Rollback skill-mcp-manager, model-availability, index.ts splits that broke tests
- Fix all import path depths for moved files (../../ -> ../../../)
- Add explicit type annotations to resolve TS7006 implicit any errors

Typecheck: 0 errors
Tests: 2359 pass, 5 fail (all pre-existing)

src/hooks/session-recovery/resume.ts

@@ -0,0 +1,39 @@
+import type { createOpencodeClient } from "@opencode-ai/sdk"
+import type { MessageData, ResumeConfig } from "./types"
+
+const RECOVERY_RESUME_TEXT = "[session recovered - continuing previous task]"
+
+type Client = ReturnType<typeof createOpencodeClient>
+
+export function findLastUserMessage(messages: MessageData[]): MessageData | undefined {
+  for (let i = messages.length - 1; i >= 0; i--) {
+    if (messages[i].info?.role === "user") {
+      return messages[i]
+    }
+  }
+  return undefined
+}
+
+export function extractResumeConfig(userMessage: MessageData | undefined, sessionID: string): ResumeConfig {
+  return {
+    sessionID,
+    agent: userMessage?.info?.agent,
+    model: userMessage?.info?.model,
+  }
+}
+
+export async function resumeSession(client: Client, config: ResumeConfig): Promise<boolean> {
+  try {
+    await client.session.promptAsync({
+      path: { id: config.sessionID },
+      body: {
+        parts: [{ type: "text", text: RECOVERY_RESUME_TEXT }],
+        agent: config.agent,
+        model: config.model,
+      },
+    })
+    return true
+  } catch {
+    return false
+  }
+}