fix(ci): address super-linter failures

- fix(update_etl): set executable bit (BASH_EXEC failure)
- fix(codespellrc): convert tab indentation to spaces (EDITORCONFIG failure)
- feat(gitleaks): add .gitleaks.toml allowlist for GA4 Measurement Protocol
  API secret in info_stats.sh (not a sensitive credential, safe to be public)
- feat(markdownlint): add .markdownlint.json matching repo list style
  (MD030 ul_multi: 1, MD007 indent: 2) to fix MARKDOWN failures

Author: dgibbs64

.github/linters/.codespellrc

@@ -1,11 +1,11 @@
 [codespell]
 # Skip data tables that contain many short server identifiers (e.g. "fof", "nd")
 skip =
-	lgsm/data/*.csv,
-	package-lock.json,
-	*/package-lock.json,
-	node_modules,
-	*/node_modules/*
+    lgsm/data/*.csv,
+    package-lock.json,
+    */package-lock.json,
+    node_modules,
+    */node_modules/*
 
 # Ignore common identifiers/acronyms and extensions used throughout LinuxGSM
 ignore-words-list = distroname,fof,nd,sav,parms,ThirdParty

.github/linters/.gitleaks.toml

@@ -0,0 +1,9 @@
+title = "LinuxGSM Gitleaks Config"
+
+[allowlist]
+  description = "Known false positives"
+  regexes = [
+    # Google Analytics 4 Measurement Protocol API secret - not a sensitive credential,
+    # it is intentionally embedded in client-side code and is safe to be public.
+    '''apisecret="[A-Za-z0-9_\-]+"''',
+  ]

.github/linters/.markdownlint.json

@@ -0,0 +1,4 @@
+{
+  "MD007": { "indent": 2 },
+  "MD030": { "ul_single": 1, "ul_multi": 1 }
+}