Phase 1/3 of DEBT-039. Adds the Python emitter-side counterpart to
auth-helper.c's sd_escape + base64 logic so service templates can
emit the universal credential SD shape with a single spread:
_log("auth_attempt", principal=user, **encode_secret(password))
secret_printable mirrors the C helper's [0x20, 0x7f) → '?' contract;
secret_b64 preserves the ORIGINAL utf-8 bytes losslessly so non-ASCII
or control-byte payloads survive as fingerprinting signal even when
the printable form sanitizes them.
The canonical syslog_bridge.py is what _sync_logging_helper()
propagates into per-template build contexts at deploy time, so any
service that imports its local syslog_bridge picks this up
automatically on next rebuild.
Phase 2 migrates the six cred-emitting service templates (FTP, POP3,
IMAP, SMTP, Redis, LDAP) onto this helper. Phase 3 deletes the
ingester's legacy adapter once nothing emits the old shape.
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.
