feat(doorman): badge listener + decoder TDD + deploy scaffolding [#355]

Modern successor of the 2018 Perl doorman (snapshot in legacy/):
bash+coreutils HID decoder, HA webhook dispatch, systemd unit.
Offline decoder suite green (9 tests); shellcheck zero-warning.

Umbrella #345. Work item: https://projects.knownelement.com/issues/355

.gitignore

@@ -0,0 +1,28 @@
+# Crush internal state (track crush.json config, ignore session data)
+.crush/crush.db
+.crush/crush.db-*
+.crush/logs/
+.crush/memory/
+.crush/active-ticket
+
+# OS/editor
+.DS_Store
+*.swp
+*.swo
+*~
+\#*\#
+.\#*
+
+# Temporary files
+*.tmp
+*.bak
+*.log.tmp
+
+# Framework artifacts (Logging.sh appends $0.<Day>-<ts>.$$ log files)
+*.Monday-*
+*.Tuesday-*
+*.Wednesday-*
+*.Thursday-*
+*.Friday-*
+*.Saturday-*
+*.Sunday-*