Parser: corpus parse rate 69% -> 81%, and stop --tests from sticking

Grammar: 'using,except(x)' modifiers, '#ifx' with block branches, unions with
parameters, multi-value initializers, mixed 'name:, lvalue = call()' targets,
'push_context' with no explicit context, 'operator []=', '#foreign lib "symbol"',
keyword-named arguments such as 'remove={...}', and '#insert (options) body'.
Directive flags now require adjacency: without it, in
'(callback: (*GUID) #c_call, lpContext: *void)' the flag swallowed ', lpContext'.

procModifier is now just directiveExpr — one rule for directives in both
positions, so fixes apply everywhere.

jaitest: a '--tests' filter persisted through Gradle's configuration cache, so a
later unfiltered ./jaitest silently re-ran only that class and printed OK.
Unfiltered runs now disable the configuration cache.

MIN_CLEAN_FILES ratchets the corpus gate at 575/714.

jaitest

@@ -9,14 +9,24 @@
 # with `java.io.EOFException` or a missing in-progress-results bin. That is an
 # infrastructure failure, not a test failure, so it is retried once.
 #
+# A `--tests` filter STICKS: Gradle reuses the configuration cache entry from the
+# previous run, so a later unfiltered `./jaitest` silently re-runs just that one
+# class and reports OK. Unfiltered runs therefore disable the configuration cache,
+# which is the only reliable way to get the whole suite back.
+#
 # Usage: ./jaitest [gradle args...]      e.g. ./jaitest --tests '*Lexer*'
 set -uo pipefail
 
 cd "$(dirname "$0")" || exit 1
 
+extra=()
+if [[ " $* " != *" --tests "* ]]; then
+    extra+=(--no-configuration-cache)
+fi
+
 run_gradle() {
     rm -rf build/reports/tests/test
-    ./jaigradle cleanTest test "$@" 2>&1 | grep -vE '^\[[0-9.]+s\]\[warning\]\[cds\]'
+    ./jaigradle cleanTest test "${extra[@]}" "$@" 2>&1 | grep -vE '^\[[0-9.]+s\]\[warning\]\[cds\]'
     return "${PIPESTATUS[0]}"
 }