fix(awk): make expression format errors fatal

[chaliy]

What changed

AWK formatting errors inside sprintf expressions now stop the AWK program with exit 2 and a fatal diagnostic. Direct printf uses the same error behavior. Scripts and agents no longer receive a successful result after a rejected format width or precision.

Closes #2456.

Why

sprintf("%10001s", "x") printed an error but yielded an empty string and exit 0. A later calculation could look complete although the format cap had been hit.

Before / After

Before: awk 'BEGIN { s=sprintf("%10001s","x"); print length(s) }' printed 0, reported the width error, and exited 0.

After: the same command prints no stdout, reports awk: fatal: format width 10001 exceeds maximum (10000), and exits 2. The focused builtin_cap_security_tests::awk_format suite passes all 3 tests; the bash spec suite and 100 awk unit tests pass.

Risk

• Low. Programs that relied on successful exit after an invalid AWK format now receive exit 2. Formatting within the cap is unchanged.
• Local just pre-pr exposed two SQLite CSV differential failures against macOS host sqlite3; this PR does not change SQLite. Required Linux CI is the merge gate.

Checklist

• Tests added or updated
• Backward compatibility considered

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