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/config/schema/hooks.ts

@@ -0,0 +1,51 @@
+import { z } from "zod"
+
+export const HookNameSchema = z.enum([
+  "todo-continuation-enforcer",
+  "context-window-monitor",
+  "session-recovery",
+  "session-notification",
+  "comment-checker",
+  "grep-output-truncator",
+  "tool-output-truncator",
+  "question-label-truncator",
+  "directory-agents-injector",
+  "directory-readme-injector",
+  "empty-task-response-detector",
+  "think-mode",
+  "subagent-question-blocker",
+  "anthropic-context-window-limit-recovery",
+  "preemptive-compaction",
+  "rules-injector",
+  "background-notification",
+  "auto-update-checker",
+  "startup-toast",
+  "keyword-detector",
+  "agent-usage-reminder",
+  "non-interactive-env",
+  "interactive-bash-session",
+
+  "thinking-block-validator",
+  "ralph-loop",
+  "category-skill-reminder",
+
+  "compaction-context-injector",
+  "compaction-todo-preserver",
+  "claude-code-hooks",
+  "auto-slash-command",
+  "edit-error-recovery",
+  "delegate-task-retry",
+  "prometheus-md-only",
+  "sisyphus-junior-notepad",
+  "start-work",
+  "atlas",
+  "unstable-agent-babysitter",
+  "task-reminder",
+  "task-resume-info",
+  "stop-continuation-guard",
+  "tasks-todowrite-disabler",
+  "write-existing-file-guard",
+  "anthropic-effort",
+])
+
+export type HookName = z.infer<typeof HookNameSchema>