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/profiler/behave_shell/_features/__init__.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Registered feature functions.
 
 Each entry takes a ``SessionContext`` and yields zero or more

decnet/profiler/behave_shell/_features/_emit.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Helper for building registry-valid :class:`Observation` records.
 
 Every feature module would otherwise repeat the same Window /

decnet/profiler/behave_shell/_features/cognitive.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """``cognitive.*`` feature functions.
 
 Step 5: ``cognitive.inter_command_latency_class``.

decnet/profiler/behave_shell/_features/emotional_valence.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """``emotional_valence.*`` feature functions (Phase G, soft block).
 
 All four primitives in this module ride a hard 0.5 confidence cap

decnet/profiler/behave_shell/_features/environmental.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """``environmental.*`` feature functions.
 
 Phase F ships the five environmental primitives plus F.0's shared

decnet/profiler/behave_shell/_features/motor.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """``motor.*`` feature functions.
 
 Step 2: ``motor.input_modality`` — typed / pasted / mixed.

decnet/profiler/behave_shell/_features/operational.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """``operational.*`` feature functions (Phase G).
 
 Step G.1: ``operational.objective``.

decnet/profiler/behave_shell/_features/temporal.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """``temporal.*`` feature functions — per-session subset.
 
 Phase E ships the four ``temporal.*`` primitives that don't need