fix(dev): streamline build config for new contributors

- Add --path:src and --threads:on to nim.cfg so tests compile without manual flags
- Add tests/config.nims for automatic path resolution in test directory
- Simplify nimble task definitions (remove redundant flags now in nim.cfg)
- Fix Dockerfile.source comment: remove obsolete nimmax reference

This makes 'nim c tests/test_all.nim' and 'nimble test' work out of the box.

baradadb.nimble

@@ -15,13 +15,13 @@ requires "checksums >= 0.2.0"
 
 # Tasks
 task build_debug, "Build debug version":
-  exec "nim c -d:ssl --threads:on --debugger:native --linedir:on -o:build/baradadb src/baradadb.nim"
+  exec "nim c --debugger:native --linedir:on -o:build/baradadb src/baradadb.nim"
 
 task build_release, "Build release version":
-  exec "nim c -d:ssl --threads:on -d:release --opt:speed -o:build/baradadb src/baradadb.nim"
+  exec "nim c -d:release --opt:speed -o:build/baradadb src/baradadb.nim"
 
 task test, "Run all tests":
-  exec "nim c --path:src -d:ssl --threads:on -r tests/test_all.nim"
+  exec "nim c -r tests/test_all.nim"
 
 task bench, "Run benchmarks":
-  exec "nim c --path:src -d:ssl --threads:on -d:release -r benchmarks/bench_all.nim"
+  exec "nim c -d:release -r benchmarks/bench_all.nim"