Add the Go binding over the C ABI hub (#228)

Adds a Go binding (`bindings/go`) over the C ABI hub — the second language stecker after C#.

## What's here
- **`bindings/go`** — a cgo binding exposing all 514 indicators as idiomatic Go types with `New<Indicator>` constructors and `Update`/`Batch`/`Reset`/`Close` methods. The wrappers in `indicators_gen.go` are generated from `bindings/c/include/wickra.h` (same archetype taxonomy as the C# generator: scalar/batch, multi-output, bars, profile, profile-values, array-input). Opaque handles are freed by `Close()` with a `runtime.SetFinalizer` backstop; pointer arguments are caller-owned, panics never cross the boundary.
- **`examples/go`** — the full example suite mirroring C/C#: streaming, backtest, multi_timeframe, parallel_assets (goroutine fan-out), three strategies, and `fetch_btcusdt`/`live_binance`.
- **CI** — a `go` job builds the C ABI library, stages it, and runs `gofmt`/`go vet`/`go test` plus the offline examples on Linux, macOS and Windows.
- **Docs** — Go added to the README languages table, project layout, building/testing, CONTRIBUTING binding table + regenerate note, ARCHITECTURE, examples index, issue/PR templates, the About-description template, and the other binding READMEs.

## Linking / distribution
The binding links the prebuilt C ABI library via cgo (`libwickra.so`/`.dylib`/`wickra.dll` staged under `bindings/go/lib`, gitignored). The native libraries are already shipped per target triple by the existing `c-abi-build` release job; distribution is via the subdirectory module tag `bindings/go/vX.Y.Z` (gated), so `release.yml` needs no new publish job.

No Rust crate or `Cargo.toml` change — the Go module is standalone and additive.

Not for merge yet (gated, per request).

.github/PULL_REQUEST_TEMPLATE.md

@@ -22,7 +22,7 @@
 - [ ] `cargo clippy --workspace --all-targets -- -D warnings` is clean.
 - [ ] `cargo test --workspace` passes.
 - [ ] New behaviour has tests; bug fixes have a regression test.
-- [ ] Public API changes are mirrored in the Python / Node / WASM bindings, and the C ABI + C# binding are regenerated
+- [ ] Public API changes are mirrored in the Python / Node / WASM bindings, and the C ABI + C# + Go bindings are regenerated
       and their type stubs (If applicable).
 - [ ] The relevant page on the [documentation site](https://docs.wickra.org)
       and the `README.md` are updated (If applicable). Docs edits go to a