feat(hashline): change hashline_edit default from true to false

Hashline edit tool and companion hooks now require explicit opt-in
via `"hashline_edit": true` in config. Previously enabled by default.

- tool-registry: hashline edit tool not registered unless opted in
- create-tool-guard-hooks: hashline-read-enhancer disabled by default
- Updated config schema comment and documentation
- Added TDD tests for default behavior

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

@@ -33,7 +33,7 @@ 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) */
+  /** Enable hashline_edit tool/hook integrations (default: false) */
   hashline_edit: z.boolean().optional(),
   /** Enable model fallback on API errors (default: false). Set to true to enable automatic model switching when model errors occur. */
   model_fallback: z.boolean().optional(),