fix(config): promote hashline_edit to top-level flag

Move hashline_edit out of experimental so it is a stable top-level config with default-on runtime behavior and explicit disable support. Add migration and tests to preserve existing experimental.hashline_edit users without breaking configs.

src/config/schema/experimental.ts

@@ -17,8 +17,6 @@ export const ExperimentalConfigSchema = z.object({
   safe_hook_creation: z.boolean().optional(),
   /** Disable auto-injected <omo-env> context in prompts (experimental) */
   disable_omo_env: z.boolean().optional(),
-  /** Enable hashline_edit tool for improved file editing with hash-based line anchors */
-  hashline_edit: z.boolean().optional(),
 })
 
 export type ExperimentalConfig = z.infer<typeof ExperimentalConfigSchema>

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

@@ -33,6 +33,8 @@ export const OhMyOpenCodeConfigSchema = z.object({
   disabled_commands: z.array(BuiltinCommandNameSchema).optional(),
   /** Disable specific tools by name (e.g., ["todowrite", "todoread"]) */
   disabled_tools: z.array(z.string()).optional(),
+  /** Enable hashline_edit tool/hook integrations (default: true at call site) */
+  hashline_edit: z.boolean().optional(),
   agents: AgentOverridesSchema.optional(),
   categories: CategoriesConfigSchema.optional(),
   claude_code: ClaudeCodeConfigSchema.optional(),