feat: initial BaraDB — multimodal database engine in Nim

- LSM-Tree storage engine with WAL, bloom filter, MemTable
- BaraQL query language: lexer (80+ tokens), recursive descent parser, AST
- Vector engine: HNSW + IVF-PQ indexes, 4 distance metrics
- Graph engine: adjacency list, BFS/DFS, Dijkstra, PageRank
- Full-Text Search: inverted index, BM25 ranking, stemming, stop words
- Type system: 17 types (int/float/string/uuid/json/vector/...)
- Async TCP server
- 21 passing tests

src/barabadb/core/config.nim

@@ -0,0 +1,25 @@
+type
+  BaraConfig* = object
+    address*: string
+    port*: int
+    dataDir*: string
+    maxConnections*: int
+    walEnabled*: bool
+    compactionStrategy*: CompactionStrategy
+
+  CompactionStrategy* = enum
+    csSizeTiered = "size_tiered"
+    csLeveled = "leveled"
+
+proc defaultConfig*(): BaraConfig =
+  BaraConfig(
+    address: "127.0.0.1",
+    port: 5432,
+    dataDir: "./data",
+    maxConnections: 1000,
+    walEnabled: true,
+    compactionStrategy: csLeveled,
+  )
+
+proc loadConfig*(): BaraConfig =
+  result = defaultConfig()