feat(default-mode): auto-activate ultrawork and ralph loop without commands

Add new `default_mode` config section with two boolean fields:
- `ultrawork`: Auto-inject ultrawork mode prompt on main session start
  without requiring the "ultrawork"/"ulw" keyword. Wired through the
  keyword-detector hook — injects once per session, respects existing
  guards (non-OMO agents, planner agents, subagent sessions).
- `ralph_loop`: Auto-start ralph loop on first main session message
  without requiring /ralph-loop or /ulw-loop commands. When ultrawork
  is also enabled, the loop starts in ultrawork mode.

Usage:
  ```jsonc
  {
    "default_mode": {
      "ultrawork": true,    // Always get ultrawork prompt on start
      "ralph_loop": true    // Auto-start ralph loop
    }
  }
  ```

Files: 7 modified/added, ~65 LOC added.

src/config/index.ts

@@ -13,6 +13,7 @@ export type {
   SisyphusAgentConfig,
   ExperimentalConfig,
   DynamicContextPruningConfig,
+  DefaultModeConfig,
   RalphLoopConfig,
   TmuxConfig,
   TmuxLayout,

src/config/schema.ts

@@ -7,6 +7,7 @@ export * from "./schema/categories"
 export * from "./schema/claude-code"
 export * from "./schema/comment-checker"
 export * from "./schema/commands"
+export * from "./schema/default-mode"
 export * from "./schema/dynamic-context-pruning"
 export * from "./schema/experimental"
 export * from "./schema/fallback-models"

src/config/schema/default-mode.ts

@@ -0,0 +1,18 @@
+import { z } from "zod"
+
+export const DefaultModeConfigSchema = z.object({
+  /**
+   * Automatically inject ultrawork mode prompt on main session start
+   * without requiring "ultrawork"/"ulw" keyword in the message.
+   * The ultrawork mode system prompt is injected once per session.
+   */
+  ultrawork: z.boolean().default(false),
+  /**
+   * Automatically start ralph loop on main session start
+   * without requiring /ralph-loop or /ulw-loop commands.
+   * When ultrawork is also enabled, the loop starts in ultrawork mode.
+   */
+  ralph_loop: z.boolean().default(false),
+})
+
+export type DefaultModeConfig = z.infer<typeof DefaultModeConfigSchema>

src/config/schema/oh-my-opencode-config.ts

@@ -10,6 +10,7 @@ import { CategoriesConfigSchema } from "./categories"
 import { ClaudeCodeConfigSchema } from "./claude-code"
 import { CommentCheckerConfigSchema } from "./comment-checker"
 import { BuiltinCommandNameSchema } from "./commands"
+import { DefaultModeConfigSchema } from "./default-mode"
 import { ExperimentalConfigSchema } from "./experimental"
 import { GitMasterConfigSchema } from "./git-master"
 import { KeywordDetectorConfigSchema } from "./keyword-detector"
@@ -81,6 +82,8 @@ export const OhMyOpenCodeConfigSchema = z.object({
   tmux: TmuxConfigSchema.optional(),
   sisyphus: SisyphusConfigSchema.optional(),
   start_work: StartWorkConfigSchema.optional(),
+  /** Default mode auto-activation settings (ultrawork, ralph loop) */
+  default_mode: DefaultModeConfigSchema.optional(),
   /** Migration history to prevent re-applying migrations (e.g., model version upgrades) */
   _migrations: z.array(z.string()).optional(),
 })