docs: fix accuracy drift in SECURITY, ARCHITECTURE, THREAT_MODEL (#253)

Documentation-only accuracy fixes from the codebase audit (no code changes).

## SECURITY.md
- Supported-version policy was stale at `0.5.x` while `0.8.3` is published. Bump to the exact `0.8.3` (prose + table `0.8.3 (latest)` / `< 0.8.3`). The exact `x.y.z` form lets `bump_version.py` keep it current automatically (now wired as a touchpoint).

## ARCHITECTURE.md
- `three` → **four** binding crates (the C ABI crate was added).
- workspace diagram `214` → **514** indicators (matches the `mod`-count and `lib.rs` public-type count; now wired into the indicator-wiring automation so it self-heals).
- WASM "does not have automated tests yet" → corrected: `bindings/wasm/src/lib.rs` carries **21** `wasm-bindgen-test` cases.
- **Numerical-stability notes rewritten to match the code:** the sliding-window variance family (`StdDev`, `Variance`, `ZScore`, `Bollinger`) uses running `Σx²−mean²` with clamping (and periodic reseed for `Bollinger`), **not** Welford. True Welford is used only by `IntradayVolatilityProfile` and `SeasonalZScore` (it does not transfer cleanly to a sliding window). The **Kahan-summation** bullet is removed — no Kahan summation exists in the crate.

## THREAT_MODEL.md
- The C ABI is built with `panic = "abort"` and has no `catch_unwind`. Replace the false "catches panics so none cross the boundary" claim with the honest abort strategy (terminates deterministically instead of unwinding across the FFI boundary, which would be UB).

SECURITY.md

@@ -2,13 +2,13 @@
 
 ## Supported versions
 
-Wickra is pre-1.0. Security fixes are applied to the latest released `0.5.x`
+Wickra is pre-1.0. Security fixes are applied to the latest released `0.8.3`
 version only; please upgrade to the newest release before reporting an issue.
 
 | Version | Supported |
 | --- | --- |
-| 0.5.x (latest) | :white_check_mark: |
-| older 0.5.x | :x: |
+| 0.8.3 (latest) | :white_check_mark: |
+| < 0.8.3 | :x: |
 
 ## Reporting a vulnerability