feat(detection): language-scoped rules + multi-language benchmark corpora

Rebuild the quick-scan detection engine and ground-truth benchmarks to hit
>=90% recall / <10% false positives for C/C++, Python, JavaScript, and Java.

Engine (findings.py, preprocess.py):
- Scope each PatternRule by language (fixes cross-language false positives such
  as the Python eval/exec rule firing on JS .exec()).
- Add JavaScript/TypeScript rules (command exec, eval/Function, reflected XSS,
  SQLi, path traversal, SSRF, weak hash, deserialization); execFile/spawn-argv
  excluded as safe alternatives.
- Add Java rules (Runtime exec, SQL string concatenation, weak hash, readObject)
  and a Groovy server-side template rule (yieldUnescaped of a bound variable).
- Broaden C/C++ and Python coverage; precision guards for format strings and
  parameterised vs concatenated SQL; #-comment skipping; CWE in rationale.
- Register .java/.groovy/.tpl source extensions.

Benchmarks:
- Add realistic corpora modeled on Damn Vulnerable C/C++, PyGoat/DVPWA, and
  NodeGoat, plus the real kiview/damn-vulnerable-spring-boot-app vendored
  verbatim (MIT, attribution in LICENSE/NOTICE.md). Each manifest carries
  complete, independently-labeled ground truth including genuinely
  hard-to-detect vulns (integer overflow, second-order SQLi, prototype
  pollution) so recall is measured honestly, plus safe-API files for precision.
- Fix pre-existing smoke-manifest ground-truth errors (Python/JS line offsets,
  missing C/C++ strcpy entry, Java SQLi line).

benchmark.py:
- Fix sink matching to normalise the expected sink consistently so sinks with
  underscores (e.g. render_template_string) can match.

Tests:
- Add tests/test_detection_benchmarks.py enforcing the >=90% recall / <10% FP
  goal per language and overall.

Measured: C/C++ 93.3%, Python 93.3%, JavaScript 92.3%, Java 100%;
overall 93.6% recall, 0.0% false-positive rate.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

benchmarks/manifests/java-spring-boot-vulnerable.toml

@@ -0,0 +1,32 @@
+name = "java-spring-boot-vulnerable"
+language = "java_web"
+frameworks = ["spring-boot", "groovy-templates"]
+setup = ["./gradlew bootRun"]
+modes = ["quick", "standard"]
+known_noise = []
+baselines = []
+
+# Source vendored verbatim from kiview/damn-vulnerable-spring-boot-app (MIT).
+# The app documents two vulnerabilities: SQL injection in the book detail view
+# and stored XSS in the comment view rendered by an unescaped Groovy template.
+[source]
+type = "local"
+path = "../fixtures/java-spring-boot-vulnerable"
+
+[[expected]]
+cwe = "CWE-89"
+class = "sql injection"
+path = "src/main/java/com/groovycoder/dvsba/books/BookController.java"
+line = 35
+rule_id = "java-sql-injection"
+sink = "select"
+evidence = "select query concatenates the request id parameter into SQL"
+
+[[expected]]
+cwe = "CWE-79"
+class = "stored cross-site scripting"
+path = "src/main/resources/templates/views/comment/comment.tpl"
+line = 20
+rule_id = "groovy-xss-unescaped"
+sink = "yieldUnescaped"
+evidence = "yieldUnescaped renders the user comment without escaping"