feat: add interactive Fee Reality widget (#136)

[eaitbrahim]

Closes #136

Summary of Changes

• Created data processing script scripts/build-fee-data.mjs to extract experiment rule family metrics from docs/experiments/2026-08-21-rule-family-significance.md into data/fee-reality-experiments.json at build time.
• Integrated scripts/build-fee-data.mjs into package.json build pipeline.
• Implemented src/components/FeeRealityWidget.astro component featuring:
  • Interactive Fee (0–150 bps) and Spread/Slippage (0–25 bps) sliders.
  • Fee presets: 0 bps (Fee-Free Allowance), 40 bps (Maker Fee), 120 bps (Coinbase Taker Fee).
  • Strategy family selector (turtle_breakout, rsi_meanrev, pullback_continuation).
  • Dynamic KPI cards (Required Break-Even Win Rate, Observed Win Rate, Net Edge / Fee Drag, Profit Factor Gross → Net).
  • Dynamic SVG 100-trade equity curve chart with crosshair and hover tooltip.
  • Traceable experiment footnote linked to docs/experiments/2026-08-21-rule-family-significance.md.
• Added trilingual i18n keys (en, ar, fr) in src/i18n/ui.ts.
• Embedded <FeeRealityWidget locale={locale} /> in HomePage.astro and ComparePage.astro.

[sonarqubecloud]

Quality Gate passed

Issues
12 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud