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/prober/__init__.py

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

tests/prober/osfp/__init__.py

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

tests/prober/osfp/test_format.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Tests for the p0f v2 .fp parser (decnet/prober/osfp/p0f/format.py)."""
 from __future__ import annotations
 

tests/prober/osfp/test_provider.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Integration tests for P0fV2Provider against the vendored .fp data."""
 from __future__ import annotations
 

tests/prober/osfp/test_signature.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Tests for signature matching + scoring."""
 from __future__ import annotations
 

tests/prober/test_active_probe_registry.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Tests for ActiveProbeMeta registry and ActiveProbe ABC contract."""
 
 from __future__ import annotations

tests/prober/test_ipv6_leak.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Tests for Ipv6LeakProbe and the underlying ipv6_leak helpers.
 
 Covers:

tests/prober/test_prober_bounty.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Tests for prober bounty extraction in the ingester.
 

tests/prober/test_prober_bus.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Bus wiring for the attacker prober (DEBT-031, worker 2).
 
 The prober fingerprints observed attackers (JARM / HASSH / TCPfp) in a

tests/prober/test_prober_hassh.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Unit tests for the HASSHServer SSH fingerprinting module.
 

tests/prober/test_prober_icmp6_error.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Tests for Icmp6ErrorProbe and the underlying icmp6_error helpers.
 
 Covers:

tests/prober/test_prober_icmp_error.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Tests for IcmpErrorProbe and the underlying icmp_error helpers.
 
 Covers:

tests/prober/test_prober_jarm.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Unit tests for the JARM fingerprinting module.
 

tests/prober/test_prober_rotation.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Integration test: _run_probe threads the rotation recorder through to probes.
 
 The prober worker constructs the recorder closure at startup; here we

tests/prober/test_prober_tcpfp.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Unit tests for the TCP/IP stack fingerprinting module.
 

tests/prober/test_prober_tlscert.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Unit tests for ``decnet.prober.tlscert``.
 
 DER fixtures are synthesized at runtime via ``cryptography`` so we don't

tests/prober/test_prober_worker.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Tests for the prober worker — target discovery from the log stream and
 probe cycle behavior (JARM, HASSH, TCP/IP fingerprinting).

tests/prober/test_run_probe_driver.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Unit tests for the _run_probe generic driver."""
 
 from __future__ import annotations