Add `/tokenize` API endpoint (#2162)

* Add tokenize API endpoint to native messaging interface

- Add new 'tokenize' action to YomitanApi for text segmentation
- Uses internal parseText with fixed scanLength of 32 characters
- Returns full parsing results with readings and dictionary info
- Useful for external applications needing Japanese text tokenization

* Make scanLength configurable in tokenize endpoint

- Add scanLength as optional parameter (defaults to 10)
- Allows callers to customize tokenization granularity
- Shorter lengths for faster processing, longer for compound words

* add decriptive errors, remove default

ext/js/comm/yomitan-api.js

···
                         };
                         break;
                     }
+                    case 'tokenize': {
+                        /** @type {import('yomitan-api.js').tokenizeInput} */
+                        // @ts-expect-error - Allow this to error
+                        const {text, scanLength} = parsedBody;
+                        if (typeof text !== 'string') {
+                            throw new Error('Invalid input for tokenize, expected "text" to be a string but got ' + typeof text);
+                        }
+                        if (typeof scanLength !== 'number') {
+                            throw new Error('Invalid input for tokenize, expected "scanLength" to be a number but got ' + typeof scanLength);
+                        }
+                        const invokeParams = {
+                            text: text,
+                            optionsContext: {index: optionsFull.profileCurrent},
+                            scanLength: scanLength,
+                            useInternalParser: true,
+                            useMecabParser: false,
+                        };
+                        result = await this._invoke('parseText', invokeParams);
+                        break;
+                    }
                     default:
                         statusCode = 400;
                 }

types/ext/yomitan-api.d.ts

···
     includeMedia?: boolean;
 };
 
+export type tokenizeInput = {
+    text: string;
+    scanLength: number;
+};
+
 export type remoteVersionResponse = {
     version: number;
 };