feat: #be sketch improved schema

SCHEMA.md

+```mermaid
+erDiagram
+WORD {
+    uuid id PK
+    blob image
+    string ocr_transcription
+    float ocr_confidence
+    string usr_transcription
+    float usr_confidence
+}
+USER {
+    uuid id PK
+}
+GAME {
+    uuid id PK
+    uuid user_id FK
+    timestamp began_at
+    timestamp ended_at
+}
+CLUE {
+    uuid id PK
+    uuid word_id FK
+    uuid game_id FK
+    integer status "pending/success/failure"
+    timestamp began_at "stamp of appearance"
+    timestamp ended_at "stamp of success/failure"
+}
+SHOT {
+    uuid id PK
+    uuid game_id FK
+    uuid clue_id FK "if something matches"
+    timestamp began_at "stamp of first input"
+    timestamp ended_at "stamp of last input"
+    string typed "e.g. 'helol\b\blo\n'"
+    string final "e.g. 'hello'"
+}
+USER ||--o{ GAME : ""
+GAME ||--o{ CLUE : ""
+WORD ||--|| CLUE : ""
+GAME ||--o{ SHOT : ""
+CLUE |o--o| SHOT : ""
+```