Add watch-lint.sh and watch-tsc.sh

Both these scripts will live reload run yarn lint and tsc,
reporting errors with notify-send.

watch-lint.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+ls *.ts* | entr yarn lint | tee >(
+  while read ln; do 
+    if echo "${ln}" | grep -q "error"; then 
+      notify-send "${ln}"
+    fi
+  done
+)

watch-tsc.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+yarn tsc --watch --preserveWatchOutput | tee >(
+  while read ln; do 
+    if echo "${ln}" | grep -q "Found [^0][0-9]* error"; then 
+      notify-send "${ln}"
+    fi
+  done
+)