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/db/__init__.py

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

tests/db/mysql/__init__.py

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

tests/db/mysql/test_mysql_histogram_sql.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Inspection-level tests for the MySQL-dialect SQL emitted by MySQLRepository.
 

tests/db/mysql/test_mysql_migration.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Tests for MySQLRepository._migrate_column_types().
 

tests/db/mysql/test_mysql_url_builder.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Unit tests for decnet.web.db.mysql.database.build_mysql_url / resolve_url.
 

tests/db/test_attribution_state.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """AttributionStateRow + identity-stub repo tests — Phase 1 substrate.
 
 Mirrors ``tests/db/test_observations.py``: SQLite ``tmp_path`` factory,

tests/db/test_base_repo.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Mock test for BaseRepository to ensure coverage of abstract pass lines.
 """

tests/db/test_campaign_repo.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Tests for the Campaign clustering repo methods on SQLModelRepository."""
 from __future__ import annotations
 

tests/db/test_credential_reuse.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """CredentialReuse repo tests — upsert idempotency, list pagination, FK backfill."""
 from __future__ import annotations
 

tests/db/test_credentials.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """Credential model + repo tests — upsert, dedup, cross-service reuse."""
 from __future__ import annotations
 

tests/db/test_decky_lifecycle.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """DeckyLifecycle repo CRUD + sweep tests.
 
 State machine: pending → running → succeeded | failed.  Rows are

tests/db/test_factory.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Unit tests for the repository factory — dispatch on DECNET_DB_TYPE.
 """

tests/db/test_identity_schema.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """
 Schema-only tests for the AttackerIdentity table and the
 attackers.identity_id FK.

tests/db/test_observations.py

@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
 """ObservationRow model + repo tests — upsert idempotency,
 latest-per-primitive query, time-series ordering.