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/realism/__init__.py

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

tests/realism/llm/__init__.py

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

tests/realism/llm/test_config.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Tests for decnet.realism.llm.config and the updated factory DB-first path."""
 from __future__ import annotations
 

tests/realism/test_bodies.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Body templates produce realistic, non-empty output per content class."""
 from __future__ import annotations
 

tests/realism/test_bodies_llm.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """LLM-enriched body generation with deterministic fallback."""
 from __future__ import annotations
 

tests/realism/test_circuit_breaker.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """LLMCircuitBreaker — process-local sliding-window breaker."""
 from __future__ import annotations
 

tests/realism/test_diurnal.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Coverage for :mod:`decnet.realism.diurnal`.
 
 Two functions to exercise:

tests/realism/test_edit.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """next_iteration mutators per content class.
 
 Stage 3b — read-modify-write contract: each editor takes a previous

tests/realism/test_email_prompt.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Prompt builder behaviour: language constraint, em-dash suppression,
 deterministic mannerism injection."""
 from __future__ import annotations

tests/realism/test_llm.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """LLM backend factory + Ollama implementation."""
 from __future__ import annotations
 

tests/realism/test_naming.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Filename realism contracts.
 
 The pre-realism orchestrator emitted ``notes-1777315854.txt`` —

tests/realism/test_personas.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Persona schema parsing + active-hours window tests."""
 from __future__ import annotations
 

tests/realism/test_personas_pool.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Global persona pool — disk-backed source for fleet/shard mail deckies."""
 from __future__ import annotations
 

tests/realism/test_planner.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Realism planner — picks (decky, persona, class, action, mtime).
 
 Stage 3 ships create-only plans; the edit branch lands in 3b.  Tests

tests/realism/test_planner_config.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Operator-tunable planner knobs (apply_payload / current_payload).
 
 §3c of the realism handoff: the planner reads mutable module globals

tests/realism/test_synthetic_files_repo.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """record / update / list / pick-for-edit on the synthetic_files table.
 
 Stage 3 of the realism migration introduces the synthetic_files

tests/realism/test_synthetic_files_truncation.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """``synthetic_files.last_body`` is capped at 64 KB by the repo.
 
 The repo clips on both insert and update so callers may pass the full

tests/realism/test_taxonomy.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Coverage for :mod:`decnet.realism.taxonomy`.
 
 The enum values are persisted on ``synthetic_files.content_class`` and