Initial commit: modular bash configuration

Reinitialised repo to purge credential history.
Credential files are now gitignored with .example templates.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

00-path-helper

@@ -0,0 +1,13 @@
+# shellcheck shell=bash
+# Helper functions to safely modify PATH
+# Both check that the directory exists AND prevent duplicates on re-source
+
+# Append directory to PATH (lower priority than existing entries)
+path_append() {
+    [[ -d "$1" ]] && [[ ":$PATH:" != *":$1:"* ]] && PATH="$PATH:$1"
+}
+
+# Prepend directory to PATH (higher priority than existing entries)
+path_prepend() {
+    [[ -d "$1" ]] && [[ ":$PATH:" != *":$1:"* ]] && PATH="$1:$PATH"
+}