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"]