docs: add comprehensive project wiki for v1.0

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

droid-wiki/how-to-contribute/index.md

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+# How to contribute
+
+rustunnel is a small, focused project. Contributions should align with the project's purpose: a lab and development tunneling tool with strong security defaults.
+
+## Work pickup
+
+- Check the CI status before starting work.
+- Open issues or PRs against the `master` branch.
+- Keep changes focused. The codebase is small enough that large refactors should be discussed first.
+
+## PR process
+
+1. Run the full test suite locally: `cargo fmt --check && cargo clippy --all-targets -- -D warnings && cargo test --all-targets`
+2. Ensure E2E tests pass if your change touches the tunnel or SOCKS5 path.
+3. Write tests for new behavior. The project uses inline `#[cfg(test)]` modules.
+4. Update relevant wiki pages if your change adds or removes features.
+
+## Review expectations
+
+- Security-sensitive changes (TLS, auth, framing) get extra scrutiny.
+- All CI jobs must pass: fmt, clippy, test, build, smoke, and E2E.
+- The project runs CI on Linux, macOS, and Windows. Avoid platform-specific code unless necessary (the signal handling module is the only current exception).
+
+## Definition of done
+
+- Code is formatted with `rustfmt`.
+- Clippy warnings are resolved.
+- Tests cover the new behavior, including edge cases.
+- No `TODO` or `FIXME` comments are introduced (the project currently has zero).