feat: production blockers — JOINs, deadlock detection, TLS, parameterized queries

- JOIN execution: INNER/LEFT/RIGHT/FULL/CROSS with column disambiguation
- Deadlock detection: wait-for graph wired into TxnManager.write()
- TLS/SSL: OpenSSL via std/net for TCP wire protocol, auto self-signed certs
- Parameterized queries: ? placeholders with WireValue binding
- Wire protocol: mkQueryParams message support
- HTTP /query endpoint accepts JSON params array
- Nim client: query(sql, params) overload
- Tests: 262 passing (15 new)

All PLAN.md production blockers resolved.

src/barabadb/core/config.nim

@@ -6,6 +6,9 @@ type
     maxConnections*: int
     walEnabled*: bool
     compactionStrategy*: CompactionStrategy
+    tlsEnabled*: bool
+    certFile*: string
+    keyFile*: string
 
   CompactionStrategy* = enum
     csSizeTiered = "size_tiered"
@@ -19,6 +22,9 @@ proc defaultConfig*(): BaraConfig =
     maxConnections: 1000,
     walEnabled: true,
     compactionStrategy: csLeveled,
+    tlsEnabled: false,
+    certFile: "",
+    keyFile: "",
   )
 
 proc loadConfig*(): BaraConfig =