feat(indicators): A5b Fibonacci tools (geometric) (#172)

Completes the **Fibonacci** family with the four geometric/time tools (catalogue 373 -> 377). All extend the internal `pattern_swing` ZigZag tracker with a per-pivot bar index and a current-bar counter (additive — the chart/harmonic detectors are unaffected), and emit `Candle -> struct` outputs via custom Python/Node/WASM bindings.

| Tool | Output |
|------|--------|
| `FibFan` | three trendlines fanning from a swing start through its 38.2/50/61.8% retracement levels, extended to the current bar |
| `FibArcs` | semicircular retracement levels centred on the swing end, normalised by the leg's bar-width (chart-scale-free) |
| `FibChannel` | a sloped base trendline plus parallel lines at Fibonacci multiples of the channel width |
| `FibTimeZones` | markers at Fibonacci bar-distances (1/2/3/5/8/...) from the latest swing pivot |

The geometric tools are novel as streaming indicators; each normalises its geometry to the swing leg's bar-width so the output is chart-scale-free. Formulas are documented in each module and deep-dive.

Fully wired: core (100% unit-tested branches incl. the new `pattern_swing` bar tracking), Python/Node/WASM struct bindings, fuzz, reference + streaming-vs-batch tests.

Verification: `cargo test --workspace` green, clippy `-D warnings` clean, node 454 tests, python 768 tests.

crates/wickra-core/src/lib.rs

@@ -76,8 +76,9 @@ pub use indicators::{
     DoubleTopBottom, DownsideGapThreeMethods, Dpo, DragonflyDoji, DrawdownDuration, Dx,
     EaseOfMovement, EffectiveSpread, EhlersStochastic, ElderImpulse, Ema,
     EmpiricalModeDecomposition, Engulfing, EveningDojiStar, Evwma, FallingThreeMethods, Fama,
-    FibConfluence, FibConfluenceOutput, FibExtension, FibExtensionOutput, FibProjection,
-    FibProjectionOutput, FibRetracement, FibRetracementOutput, FibonacciPivots,
+    FibArcs, FibArcsOutput, FibChannel, FibChannelOutput, FibConfluence, FibConfluenceOutput,
+    FibExtension, FibExtensionOutput, FibFan, FibFanOutput, FibProjection, FibProjectionOutput,
+    FibRetracement, FibRetracementOutput, FibTimeZones, FibTimeZonesOutput, FibonacciPivots,
     FibonacciPivotsOutput, FisherTransform, FlagPennant, Footprint, FootprintOutput, ForceIndex,
     FractalChaosBands, FractalChaosBandsOutput, Frama, FundingBasis, FundingRate, FundingRateMean,
     FundingRateZScore, GainLossRatio, GapSideBySideWhite, GarmanKlassVolatility, Gartley,