refactor: split into idx-core library and idx-cli binary workspace

Phase 2 of docs/DESIGN.md, no behavior change:

- crates/idx-core (library): api, analysis, cache, config file handling
  and provider selection, curl_impersonate, error, ownership, runtime,
  plus the shared test fixtures. clap derives are behind an optional
  `clap` feature so the library does not require clap.
- crates/idx-cli (binary `idx`): cli/, output/, and IdxConfig (output
  format and color resolution). Package and binary names are unchanged.
- config.rs is split: file read/write and validation move to core; a
  CLI test keeps core's OUTPUT_VALUES in sync with OutputSetting.
- ownership::db::open_db/db_path drop their unused IdxConfig argument.
- One workspace version; shared dependency versions; no third-party
  version changes in Cargo.lock. LICENSE is symlinked into each crate.
- flake: workspace version, new source paths, and a per-crate package
  check (idx-cli is built from its tarball against packaged idx-core,
  since idx-core is not on crates.io yet). CI cache key, release path
  filter, and the golden whitespace-hook exclusion follow the new layout.

Parity: all 143 golden outputs match byte for byte without
regeneration; 157 core + 17 CLI unit tests (173 before plus the new
OUTPUT_VALUES sync test), 62 CLI tests pass. Live A/B against main:
16/16 stocks cases identical; ownership discover got IDX 403 on both
(exit 4 vs 1 is the phase 1 exit-code change).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/idx-core/src/analysis/technical.rs

@@ -0,0 +1,212 @@
+use serde::Serialize;
+
+#[derive(Debug, Clone, Serialize)]
+pub struct MacdResult {
+    pub macd_line: Vec<Option<f64>>,
+    pub signal_line: Vec<Option<f64>>,
+    pub histogram: Vec<Option<f64>>,
+}
+
+pub fn sma(data: &[f64], period: usize) -> Vec<Option<f64>> {
+    let mut result = vec![None; data.len()];
+    if period == 0 || period > data.len() {
+        return result;
+    }
+
+    let mut window_sum: f64 = data[..period].iter().sum();
+    result[period - 1] = Some(window_sum / period as f64);
+
+    for idx in period..data.len() {
+        window_sum += data[idx] - data[idx - period];
+        result[idx] = Some(window_sum / period as f64);
+    }
+
+    result
+}
+
+pub fn ema(data: &[f64], period: usize) -> Vec<Option<f64>> {
+    let mut result = vec![None; data.len()];
+    if period == 0 || period > data.len() {
+        return result;
+    }
+
+    let multiplier = 2.0 / (period as f64 + 1.0);
+    let seed = data[..period].iter().sum::<f64>() / period as f64;
+    result[period - 1] = Some(seed);
+
+    let mut prev = seed;
+    for idx in period..data.len() {
+        let current = ((data[idx] - prev) * multiplier) + prev;
+        result[idx] = Some(current);
+        prev = current;
+    }
+
+    result
+}
+
+pub fn rsi(closes: &[f64], period: usize) -> Vec<Option<f64>> {
+    let mut result = vec![None; closes.len()];
+    if period == 0 || closes.len() <= period {
+        return result;
+    }
+
+    let mut gains = 0.0;
+    let mut losses = 0.0;
+
+    for idx in 1..=period {
+        let change = closes[idx] - closes[idx - 1];
+        if change >= 0.0 {
+            gains += change;
+        } else {
+            losses += -change;
+        }
+    }
+
+    let mut avg_gain = gains / period as f64;
+    let mut avg_loss = losses / period as f64;
+
+    result[period] = Some(rsi_from_averages(avg_gain, avg_loss));
+
+    for idx in (period + 1)..closes.len() {
+        let change = closes[idx] - closes[idx - 1];
+        let gain = if change > 0.0 { change } else { 0.0 };
+        let loss = if change < 0.0 { -change } else { 0.0 };
+
+        avg_gain = ((avg_gain * (period as f64 - 1.0)) + gain) / period as f64;
+        avg_loss = ((avg_loss * (period as f64 - 1.0)) + loss) / period as f64;
+
+        result[idx] = Some(rsi_from_averages(avg_gain, avg_loss));
+    }
+
+    result
+}
+
+fn rsi_from_averages(avg_gain: f64, avg_loss: f64) -> f64 {
+    if avg_loss == 0.0 {
+        return 100.0;
+    }
+
+    let rs = avg_gain / avg_loss;
+    100.0 - (100.0 / (1.0 + rs))
+}
+
+pub fn macd(closes: &[f64], fast: usize, slow: usize, signal: usize) -> MacdResult {
+    let len = closes.len();
+    let mut macd_line = vec![None; len];
+    let mut signal_line = vec![None; len];
+    let mut histogram = vec![None; len];
+
+    if len == 0 || fast == 0 || slow == 0 || signal == 0 {
+        return MacdResult {
+            macd_line,
+            signal_line,
+            histogram,
+        };
+    }
+
+    let fast_ema = ema(closes, fast);
+    let slow_ema = ema(closes, slow);
+
+    for idx in 0..len {
+        if let (Some(f), Some(s)) = (fast_ema[idx], slow_ema[idx]) {
+            macd_line[idx] = Some(f - s);
+        }
+    }
+
+    let mut signal_seed = Vec::new();
+    let signal_multiplier = 2.0 / (signal as f64 + 1.0);
+    let mut prev_signal = None;
+
+    for idx in 0..len {
+        if let Some(value) = macd_line[idx] {
+            if prev_signal.is_none() {
+                signal_seed.push(value);
+                if signal_seed.len() == signal {
+                    let seed = signal_seed.iter().sum::<f64>() / signal as f64;
+                    signal_line[idx] = Some(seed);
+                    prev_signal = Some(seed);
+                    histogram[idx] = Some(value - seed);
+                }
+            } else if let Some(prev) = prev_signal {
+                let current = ((value - prev) * signal_multiplier) + prev;
+                signal_line[idx] = Some(current);
+                prev_signal = Some(current);
+                histogram[idx] = Some(value - current);
+            }
+        }
+    }
+
+    MacdResult {
+        macd_line,
+        signal_line,
+        histogram,
+    }
+}
+
+pub fn volume_ratio(volumes: &[f64], period: usize) -> Option<f64> {
+    if period == 0 || volumes.len() < period {
+        return None;
+    }
+
+    let start = volumes.len() - period;
+    let avg = volumes[start..].iter().sum::<f64>() / period as f64;
+    if avg == 0.0 {
+        return None;
+    }
+
+    volumes.last().map(|last| *last / avg)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn approx_eq(left: f64, right: f64, eps: f64) {
+        assert!((left - right).abs() <= eps, "left={left}, right={right}");
+    }
+
+    #[test]
+    fn sma_returns_expected_values() {
+        let data = [1.0, 2.0, 3.0, 4.0, 5.0];
+        let values = sma(&data, 3);
+        assert_eq!(values, vec![None, None, Some(2.0), Some(3.0), Some(4.0)]);
+    }
+
+    #[test]
+    fn rsi_returns_seeded_none_and_known_value() {
+        // Classic Wilder example dataset; RSI(14) first computed value ~= 70.46.
+        let closes = [
+            44.34, 44.09, 44.15, 43.61, 44.33, 44.83, 45.10, 45.42, 45.84, 46.08, 45.89, 46.03,
+            45.61, 46.28, 46.28,
+        ];
+        let period = 14;
+        let values = rsi(&closes, period);
+
+        assert_eq!(values.len(), closes.len());
+        assert!(values.iter().take(period).all(Option::is_none));
+
+        let rsi_14 = values[period].expect("expected first RSI value");
+        approx_eq(rsi_14, 70.46, 0.05);
+    }
+
+    #[test]
+    fn macd_shapes_are_correct() {
+        let closes: Vec<f64> = (1..=60).map(|n| n as f64).collect();
+        let result = macd(&closes, 12, 26, 9);
+
+        assert_eq!(result.macd_line.len(), closes.len());
+
+        let macd_nones = result.macd_line.iter().filter(|v| v.is_none()).count();
+        let signal_nones = result.signal_line.iter().filter(|v| v.is_none()).count();
+        assert!(signal_nones > macd_nones);
+    }
+
+    #[test]
+    fn volume_ratio_checks() {
+        let volumes = [100.0, 120.0, 130.0, 150.0];
+        let ratio = volume_ratio(&volumes, 3).expect("ratio should exist");
+        approx_eq(ratio, 150.0 / ((120.0 + 130.0 + 150.0) / 3.0), 1e-10);
+
+        assert_eq!(volume_ratio(&volumes, 5), None);
+    }
+}