Reduce SC2016 false positives: concatenated quotes, command exceptions, BATS run flags

[Copilot]

SC2016 fires on single-quoted strings containing $-like patterns, but has a high false-positive rate across several common patterns reported in multiple open issues.

Concatenated quotes detection

When a single-quoted string is part of a word concatenated with double-quoted expansions, the user clearly understands quoting. Suppress SC2016 in this case:

# No longer warns — user demonstrably knows how quoting works
echo '$literal'"$expanded"
"${AWK[@]}" '{ print $1 }'"$inject"'more'

New command exceptions

• dash — POSIX shell like sh/bash/ksh/zsh
• gojq — Go implementation of jq
• script — runs commands via -c
• printf — format strings intentionally contain literal $

PS0 added to commonly-quoted variables

PS0 (bash 4.4+) joins PS1–PS4 and PROMPT_COMMAND as variables where single-quoted $ references are intentional.

BATS run with flags

run --separate-stderr bash -c '...' failed to resolve the effective command past flag arguments. Changed from firstArg (which bails on flags) to dropWhile isFlag args.

-- Before: fails when first arg is a flag
"run" -> firstArg
-- After: skips flags to find the actual command
"run" -> listToMaybe $ dropWhile isFlag args