feat: add extended language validators and fix tokenizer crash bugs

Expand nimcheck with validators and tokenizers for C, C++, C#, Go, Rust,
Ruby, CSS, SQL, Markdown, Dockerfile, Makefile, Kotlin, Lua, Swift,
TypeScript, and XML. Register all flavors in the validator factory and
improve auto-detection scoring for the new languages.

Fix infinite tokenizer loops that caused OOM kills: closeBracket now
advances position, finishTokenizeStep guards stalled tokenization, and
Jinja/JS tokenizers no longer double-advance on brackets.

Fix block-balance false positives in Lua (for/do) and Ruby (postfix
unless), SQL trailing-comma detection across whitespace, and Makefile
tab literals in test fixtures.

tests/fixtures/css/edge_cases.css

@@ -0,0 +1,39 @@
+:root {
+  --color-primary: #2563eb;
+}
+
+*,
+*::before,
+*::after {
+  box-sizing: border-box;
+}
+
+body {
+  font-family: "Inter", sans-serif;
+  background: var(--color-bg);
+  color: var(--color-text);
+}
+
+.navbar {
+  display: flex;
+  background: linear-gradient(135deg, var(--color-primary), #7c3aed);
+}
+
+.btn {
+  padding: 0.625rem 1.25rem;
+  border: none;
+  border-radius: 0.5rem;
+  cursor: pointer;
+  transition: background 0.2s ease;
+}
+
+@keyframes slideIn {
+  from { opacity: 0; transform: translateX(-20px); }
+  to   { opacity: 1; transform: translateX(0); }
+}
+
+@media (max-width: 600px) {
+  .navbar {
+    flex-direction: column;
+  }
+}

tests/fixtures/css/invalid.css

@@ -0,0 +1,28 @@
+:root {
+  --color-primary: #2563eb;
+}
+
+*,
+*::before,
+*::after {
+  box-sizing: border-box;
+}
+
+body {
+  font-family: "Inter", sans-serif;
+}
+
+.navbar {
+  display: flex;
+  background: linear-gradient(135deg, var(--color-primary), #7c3aed);
+}
+
+.btn {
+  padding: 0.625rem 1.25rem;
+  border: none;
+}
+
+@media (max-width: 600px) {
+  .navbar
+    flex-direction: column;
+}

tests/fixtures/css/valid.css

@@ -0,0 +1,159 @@
+:root {
+  --color-primary: #2563eb;
+  --color-primary-hover: #1d4ed8;
+  --color-bg: #f8fafc;
+  --color-text: #1e293b;
+  --color-border: #e2e8f0;
+  --radius-md: 0.5rem;
+  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
+  --font-sans: "Inter", system-ui, -apple-system, sans-serif;
+}
+
+*,
+*::before,
+*::after {
+  box-sizing: border-box;
+  margin: 0;
+  padding: 0;
+}
+
+html {
+  font-size: 16px;
+  scroll-behavior: smooth;
+}
+
+body {
+  font-family: var(--font-sans);
+  background: var(--color-bg);
+  color: var(--color-text);
+  line-height: 1.6;
+}
+
+.container {
+  max-width: 1200px;
+  margin: 0 auto;
+  padding: 0 1rem;
+}
+
+.navbar {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 1rem 2rem;
+  background: linear-gradient(135deg, var(--color-primary), #7c3aed);
+}
+
+.navbar .logo {
+  font-size: 1.5rem;
+  font-weight: 700;
+  color: #fff;
+  text-decoration: none;
+}
+
+.nav-links {
+  display: flex;
+  gap: 1.5rem;
+  list-style: none;
+}
+
+.nav-links a {
+  color: rgb(255 255 255 / 0.85);
+  text-decoration: none;
+  transition: color 0.2s ease;
+}
+
+.nav-links a:hover {
+  color: #fff;
+}
+
+.card {
+  background: #fff;
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-md);
+  box-shadow: var(--shadow-sm);
+  padding: 1.5rem;
+}
+
+.card__title {
+  font-size: 1.25rem;
+  font-weight: 600;
+  margin-bottom: 0.75rem;
+}
+
+.card__body {
+  color: #64748b;
+}
+
+.btn {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.5rem;
+  padding: 0.625rem 1.25rem;
+  border: none;
+  border-radius: var(--radius-md);
+  font-weight: 500;
+  cursor: pointer;
+  transition: background 0.2s ease, transform 0.1s ease;
+}
+
+.btn:active {
+  transform: scale(0.97);
+}
+
+.btn--primary {
+  background: var(--color-primary);
+  color: #fff;
+}
+
+.btn--primary:hover {
+  background: var(--color-primary-hover);
+}
+
+.btn--outline {
+  background: transparent;
+  border: 2px solid var(--color-primary);
+  color: var(--color-primary);
+}
+
+.grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
+  gap: 1.5rem;
+}
+
+@keyframes fadeIn {
+  from { opacity: 0; transform: translateY(10px); }
+  to   { opacity: 1; transform: translateY(0); }
+}
+
+.animate-in {
+  animation: fadeIn 0.4s ease-out both;
+}
+
+@media (max-width: 768px) {
+  .navbar {
+    flex-direction: column;
+    gap: 1rem;
+  }
+
+  .nav-links {
+    flex-wrap: wrap;
+    justify-content: center;
+  }
+
+  .grid {
+    grid-template-columns: 1fr;
+  }
+}
+
+@media (prefers-color-scheme: dark) {
+  :root {
+    --color-bg: #0f172a;
+    --color-text: #e2e8f0;
+    --color-border: #334155;
+  }
+
+  .card {
+    background: #1e293b;
+  }
+}