feat: dictionaries hold words or characters, and are asked by their source

A dictionary source now says what it holds (`kind`: `words`, the default
for files from before, or `characters`), a string so that an app older
than a new kind leaves it out. Search, countLabelled and labelled take the
dictionary by its source and meaning language, as the unique index names
it, rather than by the language: with KANJIDIC2 beside JMdict, a search
for words would otherwise bring kanji, and JLPT N5 would hold both. The
search reads the language for its query variants from the source's row;
a dictionary the instance doesn't hold finds nothing. The rank index goes
by source too.

Migration: drops and recreates dictionary_entry_rank_idx on (source,
glossLanguage, rank), and adds dictionary_source.kind, text NOT NULL
DEFAULT 'words', so a JMdict loaded before is a dictionary of words. Both
tables are reference data, never synced; the old server keeps working
until the switch (its queries by language just lose the index).

In the app, a studyset's dictionary is one of words unless a kind is
asked for.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMm7usAo6q9ZZRoPkWjoxi
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_client/lib/src/protocol/client.dart

@@ -225,8 +225,9 @@ class EndpointGitHubUpgrade extends _isc.EndpointRef {
 }
 
 /// The dictionaries the instance holds, to look words up in and to take
-/// words from by a label (all JLPT N5 words). Reference data: any signed-in
-/// person may read all of it.
+/// words from by a label (all JLPT N5 words). A dictionary is one source
+/// in one meaning language (`jmdict` in `en`). Reference data: any
+/// signed-in person may read all of it.
 /// {@category Endpoint}
 class EndpointDictionary extends _isc.EndpointRef {
   EndpointDictionary(_isc.EndpointCaller caller) : super(caller);
@@ -242,13 +243,14 @@ class EndpointDictionary extends _isc.EndpointRef {
         {},
       );
 
-  /// The entries of the dictionary of [language] with meanings in
+  /// The entries of the dictionary of [source] with meanings in
   /// [glossLanguage] that [query] finds, best first: those with a key that
   /// is the query, then a loose key that is (`sushi` for すうし), then a key
   /// starting with it, then a loose key; each in the dictionary's order. At
-  /// most [limit] (30 unless given).
+  /// most [limit] (30 unless given). None for a dictionary the instance
+  /// doesn't hold.
   _ida.Future<List<_iqbqiphu.DictionaryHit>> search(
-    String language,
+    String source,
     String glossLanguage,
     String query, {
     int? limit,
@@ -256,24 +258,24 @@ class EndpointDictionary extends _isc.EndpointRef {
     'dictionary',
     'search',
     {
-      'language': language,
+      'source': source,
       'glossLanguage': glossLanguage,
       'query': query,
       'limit': limit,
     },
   );
 
-  /// How many entries of the dictionary of [language] with meanings in
+  /// How many entries of the dictionary of [source] with meanings in
   /// [glossLanguage] carry [label].
   _ida.Future<int> countLabelled(
-    String language,
+    String source,
     String glossLanguage,
     String label,
   ) => caller.callServerEndpoint<int>(
     'dictionary',
     'countLabelled',
     {
-      'language': language,
+      'source': source,
       'glossLanguage': glossLanguage,
       'label': label,
     },
@@ -282,7 +284,7 @@ class EndpointDictionary extends _isc.EndpointRef {
   /// The entries that carry [label], in the dictionary's order: [limit] of
   /// them (100 unless given, at most [maxPage]) after the first [offset].
   _ida.Future<List<_iqbqiphu.DictionaryHit>> labelled(
-    String language,
+    String source,
     String glossLanguage,
     String label, {
     int? offset,
@@ -291,7 +293,7 @@ class EndpointDictionary extends _isc.EndpointRef {
     'dictionary',
     'labelled',
     {
-      'language': language,
+      'source': source,
       'glossLanguage': glossLanguage,
       'label': label,
       'offset': offset,

halkyon_learn_client/lib/src/protocol/dictionary/dictionary_source.dart

@@ -23,6 +23,7 @@ abstract class DictionarySource
     this.id,
     required this.source,
     required this.sourceVersion,
+    String? kind,
     required this.language,
     required this.glossLanguage,
     required this.license,
@@ -31,12 +32,13 @@ abstract class DictionarySource
     required this.fileName,
     required this.fileHash,
     required this.loadedAt,
-  });
+  }) : kind = kind ?? 'words';
 
   factory DictionarySource({
     int? id,
     required String source,
     required String sourceVersion,
+    String? kind,
     required String language,
     required String glossLanguage,
     required String license,
@@ -52,6 +54,7 @@ abstract class DictionarySource
       id: jsonSerialization['id'] as int?,
       source: jsonSerialization['source'] as String,
       sourceVersion: jsonSerialization['sourceVersion'] as String,
+      kind: jsonSerialization['kind'] as String?,
       language: jsonSerialization['language'] as String,
       glossLanguage: jsonSerialization['glossLanguage'] as String,
       license: jsonSerialization['license'] as String,
@@ -79,6 +82,11 @@ abstract class DictionarySource
   /// Its version (`3.6.2 (2026-10-05)`).
   String sourceVersion;
 
+  /// What it holds: `words` (JMdict) or `characters` (KANJIDIC2). A string
+  /// rather than an enum, so an app older than a new kind can leave out
+  /// what it doesn't know.
+  String kind;
+
   /// The words' language (`ja`).
   String language;
 
@@ -109,6 +117,7 @@ abstract class DictionarySource
     int? id,
     String? source,
     String? sourceVersion,
+    String? kind,
     String? language,
     String? glossLanguage,
     String? license,
@@ -125,6 +134,7 @@ abstract class DictionarySource
       if (id != null) 'id': id,
       'source': source,
       'sourceVersion': sourceVersion,
+      'kind': kind,
       'language': language,
       'glossLanguage': glossLanguage,
       'license': license,
@@ -143,6 +153,7 @@ abstract class DictionarySource
       if (id != null) 'id': id,
       'source': source,
       'sourceVersion': sourceVersion,
+      'kind': kind,
       'language': language,
       'glossLanguage': glossLanguage,
       'license': license,
@@ -167,6 +178,7 @@ class _DictionarySourceImpl extends DictionarySource {
     int? id,
     required String source,
     required String sourceVersion,
+    String? kind,
     required String language,
     required String glossLanguage,
     required String license,
@@ -179,6 +191,7 @@ class _DictionarySourceImpl extends DictionarySource {
          id: id,
          source: source,
          sourceVersion: sourceVersion,
+         kind: kind,
          language: language,
          glossLanguage: glossLanguage,
          license: license,
@@ -197,6 +210,7 @@ class _DictionarySourceImpl extends DictionarySource {
     Object? id = _Undefined,
     String? source,
     String? sourceVersion,
+    String? kind,
     String? language,
     String? glossLanguage,
     String? license,
@@ -210,6 +224,7 @@ class _DictionarySourceImpl extends DictionarySource {
       id: id is int? ? id : this.id,
       source: source ?? this.source,
       sourceVersion: sourceVersion ?? this.sourceVersion,
+      kind: kind ?? this.kind,
       language: language ?? this.language,
       glossLanguage: glossLanguage ?? this.glossLanguage,
       license: license ?? this.license,