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/dockerfile/edge_cases.Dockerfile

@@ -0,0 +1,9 @@
+FROM alpine:3.20 as builder
+RUN apk add --no-cache gcc musl-dev make
+WORKDIR /build
+COPY . .
+RUN make release
+FROM alpine:3.20
+RUN apk add --no-cache pcre openssl
+COPY --from=builder /build/bin/app /usr/local/bin/app
+ENTRYPOINT ["app"]

tests/fixtures/dockerfile/invalid.Dockerfile

@@ -0,0 +1,12 @@
+FROM alpine:3.20 AS builder
+RUN apk add --no-cache \
+    gcc \
+    musl-dev \
+    make \
+
+FROM alpine:3.20
+
+COPY --from=builder /build/bin/app /usr/local/bin/app
+
+ENTRYPOINT ["app"
+CMD ["--help"]

tests/fixtures/dockerfile/valid.Dockerfile

@@ -0,0 +1,45 @@
+FROM alpine:3.20 AS builder
+
+RUN apk add --no-cache \
+    gcc \
+    musl-dev \
+    pcre-dev \
+    openssl-dev \
+    make \
+    git
+
+WORKDIR /build
+
+COPY . .
+
+RUN make release \
+    && strip bin/nimcheck
+
+FROM alpine:3.20 AS runtime
+
+RUN apk add --no-cache \
+    pcre \
+    openssl \
+    ca-certificates \
+    tzdata
+
+ENV TZ=UTC
+ENV NIMCHECK_LOG_LEVEL=info
+ENV NIMCHECK_THREADS=4
+
+RUN addgroup -g 1000 nimcheck \
+    && adduser -D -u 1000 -G nimcheck nimcheck
+
+COPY --from=builder /build/bin/nimcheck /usr/local/bin/nimcheck
+
+RUN chmod 755 /usr/local/bin/nimcheck
+
+WORKDIR /workspace
+
+USER nimcheck
+
+HEALTHCHECK --interval=30s --timeout=3s --retries=3 \
+    CMD nimcheck --version || exit 1
+
+ENTRYPOINT ["nimcheck"]
+CMD ["--help"]