feat(projects): the repository reads a project and what is in it

Phase 6 of docs/project-feature.md. Six methods on `MantraRepository`, with
`DatabaseMantraRepository` behind them and `NO_OP` returning empty for previews.

The two contents queries return the versions rather than the join rows. No
screen wants a join row, and the DAO resolves it in one indexed query instead of
leaving an N+1 in a view model. Both inverses are here too -- which projects a
version is part of -- because an artifact's own screen is where "what is this
for" gets asked.

Nothing in `MantraDao`. That path -- `addDialect`, `addArtifactVersion`,
`rumorOf`, `submitToGroup` -- is the old submit flow, reached now only from its
own test, and every entity a member creates is proposed for signing instead. An
`addProject` there would be a second way to create a project that bypasses the
quorum, which is the thing this feature is for.

No query by creator or owner. Both are columns and a screen that wants them has
the row; `getProjectsOwnedBy` would be a query with one caller and an index to
go with it, and a room's project list is short. Add it when a screen asks.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

composeApp/src/commonMain/kotlin/press/mantra/compose/database/repository/DatabaseMantraRepository.kt

@@ -9,6 +9,7 @@ import press.mantra.compose.database.model.MantraArtifactVersion
 import press.mantra.compose.database.model.MantraChapter
 import press.mantra.compose.database.model.MantraChunk
 import press.mantra.compose.database.model.MantraDialect
+import press.mantra.compose.database.model.MantraProject
 import press.mantra.compose.database.model.MantraTranslationArtifactVersion
 import press.mantra.compose.database.model.MantraTranslationChapter
 import press.mantra.compose.database.model.MantraTranslationChunk
@@ -41,6 +42,35 @@ class DatabaseMantraRepository(
     override suspend fun getChaptersForArtifactVersion(artifactVersionId: String): List<MantraChapter> =
         database.mantraChapterDao().getChaptersByArtifactVersionId(artifactVersionId)
 
+    override suspend fun getProjects(chatRoomId: String): List<MantraProject> =
+        database.mantraProjectDao().getProjectsByChatRoomId(chatRoomId)
+
+    override suspend fun getProject(id: String): MantraProject? =
+        database.mantraProjectDao().getProjectById(id)
+
+    override suspend fun getProjectArtifactVersions(
+        projectId: String
+    ): List<MantraArtifactVersion> =
+        database.mantraProjectArtifactVersionDao().getArtifactVersionsByProjectId(projectId)
+
+    override suspend fun getProjectTranslationArtifactVersions(
+        projectId: String
+    ): List<MantraTranslationArtifactVersion> =
+        database.mantraProjectTranslationArtifactVersionDao()
+            .getTranslationArtifactVersionsByProjectId(projectId)
+
+    override suspend fun getProjectsForArtifactVersion(
+        artifactVersionId: String
+    ): List<MantraProject> =
+        database.mantraProjectArtifactVersionDao()
+            .getProjectsByArtifactVersionId(artifactVersionId)
+
+    override suspend fun getProjectsForTranslationArtifactVersion(
+        translationArtifactVersionId: String
+    ): List<MantraProject> =
+        database.mantraProjectTranslationArtifactVersionDao()
+            .getProjectsByTranslationArtifactVersionId(translationArtifactVersionId)
+
     override suspend fun getChapter(id: String): MantraChapter? =
         database.mantraChapterDao().getChapterById(id)
 

composeApp/src/commonMain/kotlin/press/mantra/compose/repository/MantraRepository.kt

@@ -6,6 +6,7 @@ import press.mantra.compose.database.model.MantraArtifactVersion
 import press.mantra.compose.database.model.MantraChapter
 import press.mantra.compose.database.model.MantraChunk
 import press.mantra.compose.database.model.MantraDialect
+import press.mantra.compose.database.model.MantraProject
 import press.mantra.compose.database.model.MantraTranslationArtifactVersion
 import press.mantra.compose.database.model.MantraTranslationChapter
 import press.mantra.compose.database.model.MantraTranslationChunk
@@ -56,6 +57,31 @@ interface MantraRepository {
 
     suspend fun getDialect(id: String): MantraDialect?
 
+    suspend fun getProjects(chatRoomId: String): List<MantraProject>
+
+    suspend fun getProject(id: String): MantraProject?
+
+    /**
+     * The source versions a project is translating from.
+     *
+     * The versions, not the join rows: no screen wants a join row, and resolving
+     * it here is one indexed query instead of an N+1 in a view model.
+     */
+    suspend fun getProjectArtifactVersions(projectId: String): List<MantraArtifactVersion>
+
+    /** The translations a project is producing. */
+    suspend fun getProjectTranslationArtifactVersions(
+        projectId: String
+    ): List<MantraTranslationArtifactVersion>
+
+    /** The inverse: which projects a source version is part of. */
+    suspend fun getProjectsForArtifactVersion(artifactVersionId: String): List<MantraProject>
+
+    /** The inverse again, for a translation. */
+    suspend fun getProjectsForTranslationArtifactVersion(
+        translationArtifactVersionId: String
+    ): List<MantraProject>
+
     suspend fun addArtifactVersion(
         localChatRoom: LocalChatRoom,
         artifactId: HexKey,
@@ -102,6 +128,26 @@ interface MantraRepository {
 
             override suspend fun getDialect(id: String): MantraDialect? = null
 
+            override suspend fun getProjects(chatRoomId: String): List<MantraProject> = emptyList()
+
+            override suspend fun getProject(id: String): MantraProject? = null
+
+            override suspend fun getProjectArtifactVersions(
+                projectId: String
+            ): List<MantraArtifactVersion> = emptyList()
+
+            override suspend fun getProjectTranslationArtifactVersions(
+                projectId: String
+            ): List<MantraTranslationArtifactVersion> = emptyList()
+
+            override suspend fun getProjectsForArtifactVersion(
+                artifactVersionId: String
+            ): List<MantraProject> = emptyList()
+
+            override suspend fun getProjectsForTranslationArtifactVersion(
+                translationArtifactVersionId: String
+            ): List<MantraProject> = emptyList()
+
             override suspend fun addArtifactVersion(
                 localChatRoom: LocalChatRoom,
                 artifactId: HexKey,