chore: relicense to AGPL-3.0-or-later and add SPDX headers

Replaces LICENSE (GPLv3 -> AGPLv3) and prepends
`SPDX-License-Identifier: AGPL-3.0-or-later` to every source file
across decnet/, decnet_web/, tests/, scripts/, and tools/.

Rationale: closes the GPLv3 ASP loophole so any party operating a
modified DECNET as a network service must offer their modified
source. Personal copyright (Samuel Paschuan) + inbound=outbound
contributions make a future unilateral relicense infeasible.

- LICENSE: full AGPL-3.0 text (gnu.org/licenses/agpl-3.0.txt)
- COPYRIGHT: project copyright notice
- tools/add_spdx_headers.py: idempotent header injector
  (shebang- and PEP 263-aware)

Touches 1565 source files (.py, .ts, .tsx, .js, .jsx, .css, .sh).
No behavior change; comments only.

decnet/clustering/__init__.py

@@ -1 +1,2 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Campaign clustering — see development/CAMPAIGN_CLUSTERING.md."""

decnet/clustering/base.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Identity-resolution clusterer protocol.
 
 Each concrete clusterer (``decnet.clustering.impl.connected_components``,

decnet/clustering/campaign/__init__.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Campaign clusterer — groups resolved identities into operations.
 
 The layer above identity resolution. See

decnet/clustering/campaign/base.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Campaign clusterer protocol — layer above identity resolution.
 
 Mirrors :mod:`decnet.clustering.base` for the layer above. Each concrete

decnet/clustering/campaign/factory.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Campaign-clusterer factory.
 
 Mirrors :mod:`decnet.clustering.factory` for the campaign layer.

decnet/clustering/campaign/impl/__init__.py

@@ -0,0 +1 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later

decnet/clustering/campaign/impl/connected_components.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Connected-components campaign clusterer (v1).
 
 Builds a similarity graph over identities (the layer below — already

decnet/clustering/campaign/impl/similarity.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Similarity-graph primitives for the campaign clusterer.
 
 The campaign clusterer reads ``AttackerIdentity`` rows (the layer below)

decnet/clustering/campaign/worker.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Long-running campaign-clusterer worker.
 
 Mirrors :mod:`decnet.clustering.worker` for the layer above. Bus-woken

decnet/clustering/factory.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Clusterer factory.
 
 Returns the active :class:`~decnet.clustering.base.Clusterer` instance.

decnet/clustering/impl/__init__.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Concrete clusterer implementations.
 
 Each module here contains exactly one :class:`~decnet.clustering.base.Clusterer`

decnet/clustering/impl/connected_components.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Connected-components identity clusterer (v1).
 
 Builds a similarity graph over observations (per-IP attacker rows),

decnet/clustering/impl/similarity.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Similarity-graph primitives for the connected-components clusterer.
 
 Each function takes two :class:`Observation` projections and returns a

decnet/clustering/ukc.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Unified Kill Chain phase vocabulary (Pols, 2017).
 

decnet/clustering/worker.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Long-running identity-resolution clusterer worker.
 
 Runs :meth:`Clusterer.tick` on bus-wake or slow-tick fallback. Mirrors