fix(packaging): move templates/ into decnet/ package so they ship with pip install

The docker build contexts and syslog_bridge.py lived at repo root, which
meant setuptools (include = ["decnet*"]) never shipped them. Agents
installed via `pip install $RELEASE_DIR` got site-packages/decnet/** but no
templates/, so every deploy blew up in deployer._sync_logging_helper with
FileNotFoundError on templates/syslog_bridge.py.

Move templates/ -> decnet/templates/ and declare it as setuptools
package-data. Path resolutions in services/*.py and engine/deployer.py drop
one .parent since templates now lives beside the code. Test fixtures,
bandit exclude path, and coverage omit glob updated to match.

decnet/templates/cowrie/honeyfs/etc/hosts

@@ -0,0 +1,5 @@
+127.0.0.1	localhost
+127.0.1.1	NODE_NAME
+::1		localhost ip6-localhost ip6-loopback
+ff02::1		ip6-allnodes
+ff02::2		ip6-allrouters