Added ValueBuffer implementation and simple recording

ValueBuffer is now the default buffer object for storing data for
recording and processing purposes, a simple recording implementation has
been done, core.py example starts recording as soon as the core has
started then on exit it saves the output as a csv file through the
ValueBuffer export_csv method

src/dynalab_core/buffer.py

@@ -0,0 +1,60 @@
+# Copyright (C) 2026 Hector van der Aa <hector@h3cx.dev>
+# Copyright (C) 2026 Association Exergie <association.exergie@gmail.com>
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from collections import defaultdict
+import csv
+from pathlib import Path
+from threading import Lock
+from uuid import UUID
+
+
+class ValueBuffer:
+    def __init__(self) -> None:
+        self._samples: list[tuple[int, UUID, float]] = []
+        self._lock = Lock()
+
+    def append(self, timestamp: int, uuid: UUID, value: float) -> None:
+        with self._lock:
+            self._samples.append((timestamp, uuid, value))
+
+    def clear(self) -> None:
+        with self._lock:
+            self._samples.clear()
+
+    def __len__(self) -> int:
+        with self._lock:
+            return len(self._samples)
+
+    def export_csv(self, path: str | Path) -> None:
+        with self._lock:
+            samples = list(self._samples)
+
+        rows: dict[int, dict[UUID, float]] = defaultdict(dict)
+        signal_ids: set[UUID] = set()
+
+        for timestamp_ns, signal_id, value in samples:
+            rows[timestamp_ns][signal_id] = value
+            signal_ids.add(signal_id)
+
+        ordered_signal_ids = sorted(signal_ids, key=str)
+
+        with Path(path).open(mode="w", newline="", encoding="utf-8") as file:
+            writer = csv.writer(file)
+
+            writer.writerow(
+                ["timestamp_ns", *(str(signal_id) for signal_id in ordered_signal_ids)]
+            )
+
+            for timestamp_ns in sorted(rows):
+                timestamp_values = rows[timestamp_ns]
+
+                writer.writerow(
+                    [
+                        timestamp_ns,
+                        *(
+                            timestamp_values.get(signal_id, "")
+                            for signal_id in ordered_signal_ids
+                        ),
+                    ]
+                )