Add C-family (Objective-C/C/C++) declaration parsing support

Extends symbol extraction to mixed Swift+C-family packages via clangd
multiplexing through sourcekit-lsp: new CFamilyDeclarationParser,
CompilationDatabaseWriter, ObjectiveCShimWriter, SourceLanguage detection,
PathFilter, and ShapeSnapshot, plus a shared DeclarationParser contract and
build/test scripts.

run_tests.sh

@@ -0,0 +1,53 @@
+#!/bin/bash
+set -u
+
+LIBAVCODEC_MAJOR=$(pkg-config --modversion libavcodec 2>/dev/null | cut -d. -f1)
+export LIBAVCODEC_MAJOR="${LIBAVCODEC_MAJOR:-0}"
+
+OUTFILE=$(mktemp /tmp/test_output_XXXXXX.txt)
+START_TIME=$SECONDS
+
+TEST_FILTER="${1:-}"
+shift $(( $# > 0 ? 1 : 0 ))
+
+SWIFT_TEST_ARGS=()
+if [ -n "$TEST_FILTER" ]; then
+    SWIFT_TEST_ARGS+=(--filter "$TEST_FILTER")
+fi
+if [ $# -gt 0 ]; then
+    SWIFT_TEST_ARGS+=("$@")
+fi
+
+swift test "${SWIFT_TEST_ARGS[@]}" >"$OUTFILE" 2>&1
+STATUS=$?
+ELAPSED=$((SECONDS - START_TIME))
+
+if [ -n "$TEST_FILTER" ]; then
+    echo "Filter: $TEST_FILTER"
+else
+    echo "Filter: all tests"
+fi
+
+SUMMARY_LINE=$(
+    grep -E "Executed [0-9]+ test(s)?, with [0-9]+ failures" "$OUTFILE" | tail -1
+)
+SUITE_RESULT_LINE=$(
+    grep -E "Test Suite '([^']+|Selected tests|All tests)' (passed|failed)" "$OUTFILE" | tail -1
+)
+if [ -n "$SUMMARY_LINE" ]; then
+    TOTAL_TESTS=$(printf '%s\n' "$SUMMARY_LINE" | awk '{print $2}')
+    TOTAL_FAILURES=$(printf '%s\n' "$SUMMARY_LINE" | awk '{print $5}')
+    echo "Total: $TOTAL_TESTS   Failures: $TOTAL_FAILURES"
+else
+    echo "Total: unknown   Failures: unknown"
+fi
+if [ -n "$SUITE_RESULT_LINE" ]; then
+    echo "Result: $SUITE_RESULT_LINE"
+fi
+echo "Elapsed: ${ELAPSED}s"
+echo "Build / compile errors:"
+grep -E "^/home/$(whoami)/Projects/CodeMapper/(Sources|Tests)/.*error:" "$OUTFILE" | sed "s|/home/$(whoami)/Projects/CodeMapper/||" | head -10 || echo "  none"
+echo "Failed / crashed:"
+grep "FAILED\|Fatal error\|Exited with unexpected\| failed (" "$OUTFILE" || echo "  none"
+echo "Full output: $OUTFILE"
+exit $STATUS