Initial offline process implementation

Implemented the initial offline processing implementation, with
dependency layer building and ordered processing

Processing is still single threaded and unoptimized so it can take some
time to complete, the next step is to move from a single threaded design
to a ThreadPoolExecutor that splits up the buffer into a set number of
chunks for processing

src/dynalab_core/dlpak.py

@@ -2,6 +2,7 @@
 # Copyright (C) 2026 Association Exergie <association.exergie@gmail.com>
 # SPDX-License-Identifier: GPL-3.0-or-later
 
+from __future__ import annotations
 from copy import copy
 from datetime import datetime, timezone
 import logging
@@ -59,6 +60,51 @@ class DLPak:
             timestamp=timestamp, signals=manifest_signals, comments=""
         )
 
+    def merge(self, dlpak: DLPak) -> None:
+        for sample in dlpak._data._samples:
+            self._data.append(sample[0], sample[1], sample[2])
+        self._data.sort()
+
+        for signal in dlpak._manifest.signals:
+            self._manifest.signals.append(signal)
+        log.debug(
+            "Merged %d sample(s) and %d signal(s) into DLPak",
+            len(dlpak._data),
+            len(dlpak._manifest.signals),
+            extra={
+                "event": "dlpak.merged",
+                "added_sample_count": len(dlpak._data),
+                "added_signal_count": len(dlpak._manifest.signals),
+            },
+        )
+
+    def remove_derived(self) -> None:
+        if self._manifest is not None:
+            original_sample_count = len(self._data)
+            remove_uuids = [
+                signal.id
+                for signal in self._manifest.signals
+                if signal.origin == "derived"
+            ]
+            for remove_uuid in remove_uuids:
+                self._data.clear_uuid(remove_uuid)
+
+            self._manifest.signals = [
+                signal
+                for signal in self._manifest.signals
+                if signal.origin != "derived"
+            ]
+            log.debug(
+                "Removed %d derived signal(s) and %d sample(s) from DLPak",
+                len(remove_uuids),
+                original_sample_count - len(self._data),
+                extra={
+                    "event": "dlpak.derived_removed",
+                    "removed_signal_count": len(remove_uuids),
+                    "removed_sample_count": original_sample_count - len(self._data),
+                },
+            )
+
     def get_all_signal_descriptors(self) -> list[SignalDescriptor]:
         return copy([signal.to_pure() for signal in self._manifest.signals])