chore: initial project skeleton

Acauã: Network Detection & Threat Hunting, heuristic analysis over a
rolling 7-day window using deterministic math (time series, graph
theory, information theory) instead of opaque ML models. Third
product in the Ciberfauna ecosystem, alongside Guará and Sabiá.

Follows the ecosystem's established conventions: OpenWolf project
memory, bilingual PT-BR/EN docs and UI, Gitea Actions CI/CD on the
same self-hosted runners, Conventional Commits, SemVer, logo and
productName handling, MIT OR Apache-2.0 licensing.

Architecture decision (made with the project owner after a dedicated
consultation, not the original blueprint's suggested stack): Rust
throughout, not Python/FastAPI/React. Most of the statistics (Bowley
skew, MADM, Shannon entropy, PCR, Z-score, novel-edge detection,
pivot chains) reduces to SQL over an embedded DuckDB/Parquet store;
only the spectral analysis and graph centrality need host-language
code, and both have workable Rust crates. Documented in full, including
six corrections to the original blueprint's math (Rayleigh/Schuster
instead of a degenerate Lomb-Scargle over bare timestamps, an explicit
sentinel for Bowley skew's Q3=Q1 case, Jensen-Shannon instead of
unbounded KL, a dedicated long-connection detector, JA4 vs. JA4+
licensing caution, deterministic per-alert evidence), in
docs/architecture.md.

Skeleton only: crates/acaua-core has the four detection pillars,
fusion, storage, zeek log parsing and the updater as typed stubs that
compile and return a clear "skeleton" status rather than real
detection logic — that is separate, future work. crates/acaua-cli has
serve/analyze/doctor/update. apps/gui is a minimal Tauri shell. Also
already includes the one-click desktop self-update mechanism shared
with Guará and Sabiá (AppImage/.deb/Windows installer), even with no
release published yet, for consistency across the ecosystem.

No Gitea repository exists for this project yet; this is a local-only
commit.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VAyr8d7HuAdUGB6aA5xmDD

SECURITY.md

@@ -0,0 +1,44 @@
+# Security policy
+
+**English** · [Português](SECURITY.pt-BR.md)
+
+Acauã is defensive software, but it processes hostile input: packet captures,
+Zeek logs and flow records may be malformed on purpose. Treat every dataset as
+untrusted.
+
+## Reporting a vulnerability
+
+Do not open a public issue with exploit details. Open a minimal issue asking for
+a private channel, or contact the maintainer through the Gitea profile listed on
+the repository. Include the affected version, the input shape and a minimal
+reproduction when a private channel is available.
+
+## Scope and threat model
+
+- **Input parsing:** a malformed log line must not panic the daemon, exhaust
+  memory or escape the configured data directory.
+- **Path handling:** dataset paths are resolved and confined to the configured
+  root; symbolic links are not followed outside it.
+- **API exposure:** `serve` binds to `127.0.0.1` by default. Exposing it on a
+  network interface is an explicit operator decision and needs a reverse proxy
+  with authentication.
+- **Evidence integrity:** alert evidence must be reproducible from the same
+  input and code version. Silent nondeterminism is a correctness and security
+  issue.
+- **Updates:** the CLI checks Gitea Releases, downloads over HTTPS and verifies
+  SHA-256 before replacing the binary. The desktop app does not update itself.
+- **Privacy:** there is no telemetry. Retention defaults to seven days of
+  normalized events; the operator is responsible for local law and policy.
+
+## Out of scope
+
+- Vulnerabilities in third-party Zeek, Suricata, Tauri or operating-system
+  packages that are already fixed upstream.
+- Attacks that require the operator to disable the documented security controls
+  (for example, running `serve` as root on a public interface).
+- Detection quality claims: the pillars are not implemented in this skeleton.
+
+## Supported versions
+
+Only the latest `0.1.x` line is supported while the project is pre-alpha. There
+is no long-term support branch yet.