docs(plan): v0.5.0 plans A/B and doc audit
Plan A (Rust + docs): S1 pre-receive hook fix, S2 tar
path-traversal hardening, S3 RELICARIO_* env-var audit, C1
stale branch cleanup. ~9 tasks, ~50 steps.
Plan B (extension UX): P4 error-copy centralization (subsumes
B2), B1 strength-meter regenerate fix, P1 password coloring
(inlined), P3 form-layout envelope, P2 setup → fullscreen tab.
~15 tasks, ~85 steps.
Doc audit: 14 findings, 6 fixed inline (README, ARCHITECTURE,
overview), 8 proposed for v0.5.0 release prep.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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