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.

tests/clustering/__init__.py

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

tests/clustering/fixture_harness.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Shared helpers for fixture-driven clustering tests.
 

tests/clustering/metrics.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Clustering metric harness — see development/CAMPAIGN_CLUSTERING.md §3.
 

tests/clustering/test_campaign_factory.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Determinism + DSL-validation tests for the synthetic campaign factory."""
 from __future__ import annotations
 

tests/clustering/test_campaign_similarity.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Tests for campaign-level similarity primitives.
 
 Covers, in order:

tests/clustering/test_campaign_worker.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """End-to-end tests for the campaign-clusterer worker shell + tick.
 
 Mirrors :mod:`tests.clustering.test_clusterer_worker` for the layer

tests/clustering/test_clusterer_factory.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Tests for :mod:`decnet.clustering.factory`."""
 from __future__ import annotations
 

tests/clustering/test_clusterer_worker.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """End-to-end tests for the clusterer worker shell.
 
 The skeleton clusterer is a no-op; these tests cover the shell:

tests/clustering/test_connected_components.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Tests for the connected-components clusterer (commit 4 — high-weight edges).
 
 Covers, in order:

tests/clustering/test_fixtures_campaign_clusterer.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Run the production campaign clusterer through all 7 fixtures.
 
 The 7 fixtures' YAML bounds were tuned for *reference* clusterers

tests/clustering/test_lone_wolf_fixture.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 End-to-end pipeline test for fixture 3 (lone_wolf).
 

tests/clustering/test_metrics.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Sanity tests for the clustering metric harness."""
 from __future__ import annotations
 

tests/clustering/test_multi_operator_fixture.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 End-to-end pipeline test for fixture 5 (multi_operator).
 

tests/clustering/test_noise_floor_fixture.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 End-to-end pipeline test for fixture 6 (noise_floor).
 

tests/clustering/test_paused_campaign_fixture.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 End-to-end pipeline test for fixture 4 (paused_campaign).
 

tests/clustering/test_shared_wordlist_fixture.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 End-to-end pipeline test for fixture 1 (shared_wordlist).
 

tests/clustering/test_similarity.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Unit tests for the similarity-graph primitives.
 
 Each edge function is tested in isolation: agreement → high score,

tests/clustering/test_slow_burn_fixture.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 End-to-end pipeline test for fixture 7 (slow_burn).
 

tests/clustering/test_ttp_phase_handoff.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """E.3.15 — production phase-handoff edge fires from ttp_tag rows.
 
 The UKC bridge (``tactic_to_ukc_phase`` + ``OBSERVABLE_PHASES``) was

tests/clustering/test_ukc_bridge.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """E.2.9 — UKC bridge bijection tests.
 
 Pins the ATT&CK tactic ↔ UKC phase mapping declared in

tests/clustering/test_vpn_hopping_fixture.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 End-to-end pipeline test for fixture 2 (vpn_hopping).
 

tests/clustering/test_worker_publish.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Clusterer publishes ``identity.formed`` and ``identity.merged``.
 
 Pins the producer wiring. The clusterer reports its tick output via a