C ABI: full example suite + docs & About coverage (#224)

Stacked on #222 (base `feat/c-abi-hub`), so the diff is just the additions on top of the hub foundation — no merge of #222 required.

## What this adds

**Examples — full parity with rust/python/node (`examples/c/`)**
- `streaming.c` upgraded to the multi-indicator (SMA/EMA/RSI/MACD + signals) demo
- `backtest.c`, `multi_timeframe.c` (manual time-bucket resampling), `parallel_assets.c` (serial vs OpenMP fan-out, one handle per asset)
- three educational strategies: `strategy_rsi_mean_reversion.c`, `strategy_macd_adx.c`, `strategy_bollinger_squeeze.c`
- two network examples shelling out to `curl`: `fetch_btcusdt.c`, `live_binance.c` (REST poll)
- two header-only helpers (`wickra_csv.h`, `wickra_strategy.h`) since the C ABI ships no IO layer
- CMake builds all 11; the 9 offline ones run under `ctest` on 3 OS; the network two are built-only

**Docs & metadata — surface the C ABI everywhere it was missing**
- ARCHITECTURE diagram + crate table, SECURITY + THREAT_MODEL (the C ABI as the sole `unsafe` FFI surface), the three binding package READMEs, issue/PR templates, CHANGELOG, and the GitHub About template (live About + org description updated too)

**Cleanup**
- removed all references to the private generator tooling from public files (`bindings/c/src/lib.rs` header, `CONTRIBUTING.md`, `sync-about.yml`)

Verified locally: `cargo build -p wickra-c --release`, `cmake + ctest` (9/9 pass), and `-Wall -Wextra -Wpedantic` clean on gcc 13.

bindings/c/src/lib.rs

@@ -11,9 +11,8 @@
 //! - `wickra_<ind>_free(h)` — destroy the handle. Every `_new` must be paired
 //!   with exactly one `_free`; there is no RAII across the C boundary.
 //!
-//! GENERATED by the `ScriptHelpers` `capi` wrapper from the Rust core. Do not edit
-//! by hand — edit the generator and regenerate, then commit this file and
-//! `include/wickra.h`.
+//! GENERATED from the Wickra core. Do not edit by hand — regenerate from the
+//! core and commit this file together with `include/wickra.h`.
 
 use core::ptr;
 use core::slice;

bindings/node/README.md

@@ -9,7 +9,8 @@
 prebuilt native binary, no system dependencies.**
 
 Wickra is a multi-language technical-analysis library with a Rust core and
-bindings for Python, Node.js, and WebAssembly. Every indicator is an O(1)
+bindings for Python, Node.js and WebAssembly, plus a C ABI for C/C++ and any
+other C-capable language. Every indicator is an O(1)
 streaming state machine, so live trading bots and historical backtests share
 the exact same implementation. This package is the Node.js binding (napi-rs);
 it exposes 200+ streaming-first indicators across sixteen families.
@@ -55,8 +56,9 @@ the main repository and documentation site:
 - **Docs** (quickstarts, cookbook, TA-Lib migration): <https://docs.wickra.org>
 - **Runnable examples:** [`examples/node/`](https://github.com/wickra-lib/wickra/tree/main/examples/node)
 
-Wickra ships four bindings — Python, Node.js, WebAssembly, and Rust — that all
-expose the same indicators from the shared, `unsafe`-forbidden Rust core.
+Wickra ships native bindings for Python, Node.js, WebAssembly and Rust, plus a
+C ABI hub that any C-capable language (C, C++, Go, C#, Java, R) links against —
+all exposing the same indicators from the shared, `unsafe`-forbidden Rust core.
 
 ## Disclaimer
 

bindings/python/README.md

@@ -9,7 +9,8 @@
 system dependencies, no C build tooling.**
 
 Wickra is a multi-language technical-analysis library with a Rust core and
-bindings for Python, Node.js, and WebAssembly. Every indicator is an O(1)
+bindings for Python, Node.js and WebAssembly, plus a C ABI for C/C++ and any
+other C-capable language. Every indicator is an O(1)
 streaming state machine, so live trading bots and historical backtests share
 the exact same implementation. This package is the Python binding (PyO3); it
 exposes 200+ streaming-first indicators across sixteen families.
@@ -54,8 +55,9 @@ the main repository and documentation site:
 - **Docs** (quickstarts, cookbook, TA-Lib migration): <https://docs.wickra.org>
 - **Runnable examples:** [`examples/python/`](https://github.com/wickra-lib/wickra/tree/main/examples/python)
 
-Wickra ships four bindings — Python, Node.js, WebAssembly, and Rust — that all
-expose the same indicators from the shared, `unsafe`-forbidden Rust core.
+Wickra ships native bindings for Python, Node.js, WebAssembly and Rust, plus a
+C ABI hub that any C-capable language (C, C++, Go, C#, Java, R) links against —
+all exposing the same indicators from the shared, `unsafe`-forbidden Rust core.
 
 ## Disclaimer
 

bindings/wasm/README.md

@@ -9,7 +9,8 @@
 wickra-wasm` — pure WebAssembly, runs anywhere a modern JS engine does.**
 
 Wickra is a multi-language technical-analysis library with a Rust core and
-bindings for Python, Node.js, and WebAssembly. Every indicator is an O(1)
+bindings for Python, Node.js and WebAssembly, plus a C ABI for C/C++ and any
+other C-capable language. Every indicator is an O(1)
 streaming state machine, so live trading dashboards and historical backtests
 share the exact same implementation. This package is the WebAssembly binding
 (wasm-bindgen, built for the `web` target); it exposes 200+ streaming-first
@@ -54,8 +55,9 @@ the main repository and documentation site:
 - **Docs** (quickstarts, cookbook, TA-Lib migration): <https://docs.wickra.org>
 - **Runnable browser examples:** [`examples/wasm/`](https://github.com/wickra-lib/wickra/tree/main/examples/wasm)
 
-Wickra ships four bindings — Python, Node.js, WebAssembly, and Rust — that all
-expose the same indicators from the shared, `unsafe`-forbidden Rust core.
+Wickra ships native bindings for Python, Node.js, WebAssembly and Rust, plus a
+C ABI hub that any C-capable language (C, C++, Go, C#, Java, R) links against —
+all exposing the same indicators from the shared, `unsafe`-forbidden Rust core.
 
 ## Disclaimer