Stacked on #315 (the native Binance REST fetcher). Retarget to `main` once #315 merges.
Migrates the runnable examples off third-party data-I/O packages onto Wickra's
native data layer (`CandleReader`, `Resampler`, `BinanceFeed`, `fetch_*klines`).
## Third-party packages removed (the zero-dep selling point)
- **Node**: `ws` (live feed → BinanceFeed) — dropped from package.json + lockfile
- **Go**: `github.com/coder/websocket` — dropped from go.mod / go.sum (`go mod tidy`)
- **Java**: `jackson-databind` (live feed + REST fetch) — dropped from pom.xml
- **R**: `jsonlite` + `websocket` + `later` — dropped from the README notes
Each language's CSV loading now goes through `CandleReader`, manual resampling
through `Resampler`, the live feed through `BinanceFeed`, and (Java/R) the REST
download through the native fetcher.
## Verification
Ran the offline examples per language against the bundled data — backtest and
multi_timeframe produce identical output across Python / Node / Go / Java / R
(e.g. ATR(14) last 345.1010; 1h→5m resamples to 240 bars, →15m to 80 bars).
C# / C / WASM (stdlib-only, no third-party deps to remove) follow in this branch.
Note: the streaming `strategy_*` examples have pre-existing candle-indicator
runtime bugs (CI only syntax-smokes them); the CSV migration preserves their
shape and leaves those bugs for a separate fix.
Continue the per-language `examples/<lang>/` restructure: move the three
Node example files (streaming.js, backtest.js, live_trading.js) out of
bindings/node/examples/ and into a top-level examples/node/ directory.
* `examples/node/package.json` is a `private` package that pulls the
native binding via `file:../../bindings/node` and lists `ws` as a
dev-dependency for the live-trading example. `require('..')` in each
file becomes `require('wickra')` — exactly what a downstream user would
write — and the file-header run instructions are updated to the new
two-step workflow (`npm install` in bindings/node, then in
examples/node).
* `backtest.js`'s default-CSV path becomes the much shorter
`__dirname/../data/btcusdt-1d.csv` from the new location.
* `bindings/node/package.json` drops the now-unused `ws` devDependency.
* `.gitignore` is broadened from `bindings/node/node_modules/` to
`**/node_modules/` so the new `examples/node/node_modules/` directory is
not tracked.
* The README "Languages" table, project-layout block and
`examples/README.md` Node section are updated for the new paths and run
commands.
Verified by running `node backtest.js` (3200 BTCUSDT daily bars, matching
output), `node streaming.js`, and `node --check live_trading.js` from the
new location.
kingchenc