fix(adapter,executor,tests): harden nimforum adapter and fix transaction/aggregate bugs

Adapter (baradb_sqlite.nim):
- getRow now returns @[] for missing rows (db_sqlite compat)
- insertID/nextId handle NULL (\N) values correctly
- preprocessQuery replaces SQLite-specific syntax:
  TIMESTAMP->DATETIME, DATETIME('now')->current timestamp, INET->STRING
- add dbBegin/dbCommit/dbRollback for transaction support

Executor:
- fix COMMIT treating empty values as DELETE (rows with only PK were lost)
- fix MIN/MAX aggregates including NULL (\N) which skewed results
- add numeric comparison for irNeq

Tests:
- stress_test: shared DB, 16 workers, correctness scan after run
- nimforum_smoke_test: 10 tests including schema, transactions, iterators

tests/nimforum_smoke_test.nim

@@ -1,8 +1,7 @@
-## NimForum Adapter Smoke Test
+## NimForum Adapter Smoke Test — comprehensive validation
 import std/unittest
 import std/osproc
 import std/os
-import std/strutils
 import std/strtabs
 import std/times
 
@@ -24,7 +23,23 @@ suite "NimForum Adapter Smoke Test":
     env["BARADB_DATA_DIR"] = dataDir
     env["BARADB_LOG_LEVEL"] = "error"
     serverProcess = startProcess("./build/baradadb", env=env, options={poStdErrToStdOut, poDaemon})
-    sleep(800)
+    # Wait for server to be ready (with timeout)
+    var pingDb: DbConn
+    var connected = false
+    for i in 0 ..< 50:
+      sleep(100)
+      try:
+        pingDb = open("127.0.0.1:" & $port, "", "", "default")
+        connected = true
+        break
+      except:
+        discard
+    if not connected:
+      serverProcess.terminate()
+      discard serverProcess.waitForExit()
+      removeDir(dataDir)
+      raise newException(IOError, "Server failed to start")
+    pingDb.close()
 
   teardown:
     if serverProcess != nil:
@@ -67,3 +82,170 @@ suite "NimForum Adapter Smoke Test":
     check row[row.len - 1] == "ten"
 
     db.close()
+
+  test "getRow returns @[] for missing rows":
+    var db = open("127.0.0.1:" & $port, "", "", "default")
+    db.exec(sql"CREATE TABLE nf_missing (id INT PRIMARY KEY)")
+    let row = db.getRow(sql"SELECT * FROM nf_missing WHERE id = 999")
+    check row.len == 0
+    db.close()
+
+  test "insertID and nextId":
+    var db = open("127.0.0.1:" & $port, "", "", "default")
+    db.exec(sql"CREATE TABLE nf_ids (id INT PRIMARY KEY, name STRING)")
+
+    let id1 = db.insertID(sql"INSERT INTO nf_ids (id, name) VALUES (5, 'five')")
+    check id1 == 5
+
+    let next = db.nextId("nf_ids")
+    check next == 6
+
+    db.close()
+
+  test "Transactions (BEGIN/COMMIT/ROLLBACK)":
+    var db = open("127.0.0.1:" & $port, "", "", "default")
+    db.exec(sql"CREATE TABLE nf_txn (id INT PRIMARY KEY)")
+
+    db.dbBegin()
+    db.exec(sql"INSERT INTO nf_txn (id) VALUES (1)")
+    db.dbCommit()
+    check db.getValue(sql"SELECT count(*) FROM nf_txn") == "1"
+
+    db.dbBegin()
+    db.exec(sql"INSERT INTO nf_txn (id) VALUES (2)")
+    db.dbRollback()
+    check db.getValue(sql"SELECT count(*) FROM nf_txn") == "1"
+
+    db.close()
+
+  test "fastRows iterator":
+    var db = open("127.0.0.1:" & $port, "", "", "default")
+    db.exec(sql"CREATE TABLE nf_iter (id INT PRIMARY KEY)")
+    db.exec(sql"INSERT INTO nf_iter (id) VALUES (1)")
+    db.exec(sql"INSERT INTO nf_iter (id) VALUES (2)")
+    db.exec(sql"INSERT INTO nf_iter (id) VALUES (3)")
+
+    var count = 0
+    for r in db.fastRows(sql"SELECT id FROM nf_iter ORDER BY id"):
+      count.inc
+    check count == 3
+
+    db.close()
+
+  test "execAffectedRows":
+    var db = open("127.0.0.1:" & $port, "", "", "default")
+    db.exec(sql"CREATE TABLE nf_aff (id INT PRIMARY KEY, name STRING)")
+    db.exec(sql"INSERT INTO nf_aff (id, name) VALUES (1, 'a')")
+    db.exec(sql"INSERT INTO nf_aff (id, name) VALUES (2, 'b')")
+
+    let affected = db.execAffectedRows(sql"DELETE FROM nf_aff WHERE id = 1")
+    check affected == 1
+
+    db.close()
+
+  test "tryExec success and failure":
+    var db = open("127.0.0.1:" & $port, "", "", "default")
+    db.exec(sql"CREATE TABLE nf_try (id INT PRIMARY KEY)")
+
+    check db.tryExec(sql"INSERT INTO nf_try (id) VALUES (1)") == true
+    check db.tryExec(sql"INSERT INTO nf_try (id) VALUES (1)") == false
+
+    db.close()
+
+  test "NimForum schema creation":
+    var db = open("127.0.0.1:" & $port, "", "", "default")
+
+    # Create nimforum-like schema (adapter preprocesses DATETIME/TIMESTAMP/INET)
+    db.exec(sql"""
+      CREATE TABLE thread (
+        id INT PRIMARY KEY,
+        name STRING NOT NULL,
+        views INT NOT NULL,
+        modified DATETIME NOT NULL DEFAULT DATETIME('now')
+      )
+    """)
+    db.exec(sql"CREATE UNIQUE INDEX ThreadNameIx ON thread (name)")
+
+    db.exec(sql"""
+      CREATE TABLE person (
+        id INT PRIMARY KEY,
+        name STRING NOT NULL,
+        password STRING NOT NULL,
+        email STRING NOT NULL,
+        creation DATETIME NOT NULL DEFAULT DATETIME('now'),
+        salt STRING NOT NULL,
+        user_status STRING NOT NULL,
+        lastOnline DATETIME NOT NULL DEFAULT DATETIME('now'),
+        ban STRING NOT NULL DEFAULT ''
+      )
+    """)
+    db.exec(sql"CREATE UNIQUE INDEX UserNameIx ON person (name)")
+
+    db.exec(sql"""
+      CREATE TABLE post (
+        id INT PRIMARY KEY,
+        author INT NOT NULL,
+        ip STRING NOT NULL,
+        header STRING NOT NULL,
+        content STRING NOT NULL,
+        thread INT NOT NULL,
+        creation DATETIME NOT NULL DEFAULT DATETIME('now')
+      )
+    """)
+
+    db.exec(sql"""
+      CREATE TABLE session (
+        id INT PRIMARY KEY,
+        ip STRING NOT NULL,
+        password STRING NOT NULL,
+        userid INT NOT NULL,
+        lastModified DATETIME NOT NULL DEFAULT DATETIME('now')
+      )
+    """)
+
+    db.exec(sql"""
+      CREATE TABLE antibot (
+        id INT PRIMARY KEY,
+        ip STRING NOT NULL,
+        answer STRING NOT NULL,
+        created DATETIME NOT NULL DEFAULT DATETIME('now')
+      )
+    """)
+
+    db.exec(sql"CREATE INDEX PersonStatusIdx ON person(user_status)")
+    db.exec(sql"CREATE INDEX PostByAuthorIdx ON post(thread, author)")
+
+    # Insert and query forum data
+    db.exec(sql"INSERT INTO thread (id, name, views) VALUES (1, 'First Thread', 0)")
+    db.exec(sql"INSERT INTO person (id, name, password, email, salt, user_status, ban) VALUES (1, 'admin', 'pw', 'a@b.c', 'salt', 'active', '')")
+    db.exec(sql"INSERT INTO post (id, author, ip, header, content, thread) VALUES (1, 1, '127.0.0.1', 'Hello', 'World', 1)")
+
+    let threads = db.getAllRows(sql"SELECT * FROM thread")
+    check threads.len == 1
+
+    let posts = db.getAllRows(sql"SELECT * FROM post WHERE thread = 1")
+    check posts.len == 1
+
+    db.close()
+
+  test "NimForum-like operations":
+    var db = open("127.0.0.1:" & $port, "", "", "default")
+
+    db.exec(sql"CREATE TABLE nf_ops (id INT PRIMARY KEY, views INT NOT NULL)")
+    db.exec(sql"INSERT INTO nf_ops (id, views) VALUES (1, 0)")
+
+    # Update views (like nimforum does)
+    let affected = db.execAffectedRows(sql"UPDATE nf_ops SET views = views + 1 WHERE id = 1")
+    check affected == 1
+
+    let views = db.getValue(sql"SELECT views FROM nf_ops WHERE id = 1")
+    check views == "1"
+
+    # Try update with DATETIME('now') (preprocessed by adapter)
+    db.exec(sql"CREATE TABLE nf_dt (id INT PRIMARY KEY, modified DATETIME)")
+    db.exec(sql"INSERT INTO nf_dt (id, modified) VALUES (1, DATETIME('now'))")
+    let dtRow = db.getRow(sql"SELECT modified FROM nf_dt WHERE id = 1")
+    check dtRow.len == 1
+    check dtRow[0].len > 0
+
+    db.close()