v0.1.11 — audit pass-6 closure

Security: 0o600 log files (SEC-0034), symlink guard + absolute-path
opt-in (SEC-0037), full-key redaction scan (SEC-0038), truncate-with-
marker + records_truncated_total metric (SEC-0039).
Performance: multi_handler sequential dispatch ~200x fix (PERF-039),
condvar-driven async queue (PERF-040/041/042), compare-bench gate
restored (PERF-043), baseline regenerated.
Quality: examples ported to Zig 0.16 and compile-checked in CI,
29 latent-dead tests revived (suite 261 -> 306), lint/tooling fixes.