feat: NCS-37 Quarkus integration (#35)

Reviewed-on: #35
Reviewed-by: Leon Hermann <lq@blackhole.local>

docs/board-api-spec.yaml

@@ -1,6 +1,6 @@
 openapi: 3.0.3
 info:
-  title: NowChess API
+  title: NowChess Board API
   description: |
     REST API for the NowChess application. Designed to feel familiar to users
     of the [lichess API](https://lichess.org/api).
@@ -186,11 +186,8 @@ paths:
         currently to move.
 
         For promotion moves include the target piece as the fifth character:
-        `e7e8q`, `a2a1r`, etc.
-
-        If the move results in a pawn reaching the back rank and no promotion
-        character is supplied, the game enters `promotionPending` status and
-        the move is not yet applied — resubmit with the promotion character.
+        `e7e8q`, `a2a1r`, etc. Promotion moves without the fifth character
+        are rejected with `400 INVALID_MOVE`.
       security:
         - bearerAuth: []
       parameters:
@@ -630,7 +627,6 @@ components:
         | `draw` | Draw agreed or claimed — game over |
         | `drawOffered` | Waiting for the opponent to accept or decline a draw offer |
         | `fiftyMoveAvailable` | Fifty-move rule threshold reached; active player may claim draw |
-        | `promotionPending` | A pawn reached the back rank; awaiting promotion piece selection |
         | `insufficientMaterial` | Neither side has enough pieces to deliver checkmate — game over (draw) |
       enum:
         - started
@@ -641,7 +637,6 @@ components:
         - draw
         - drawOffered
         - fiftyMoveAvailable
-        - promotionPending
         - insufficientMaterial
 
     # -------------------------------------------------------------------------