chore(release): prepare v0.1.9

[AzulGarza]

Summary

• Bump foundationforecast to 0.1.9 after merging quantile interpolation (feat: quantile interpolation for arbitrary levels and quantiles #27).
• Add v0.1.9 changelog, docs nav, and README News entry.
• Sync root and gift-eval uv.lock files.

After merge (publish)

1. Tag and push: git tag v0.1.9 && git push origin v0.1.9
2. The Release workflow creates the GitHub release from docs/changelogs/v0.1.9.md and publishes to PyPI.

Test plan

• CI green on this PR
• Changelog links render in docs build

Made with Cursor

[codspeed]

Merging this PR will degrade performance by 0.16%

⚡ 1 improved benchmark
❌ 1 regressed benchmark
✅ 15 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	WallTime	test_model_forecast[timesfm-1]	2.4 s	2.7 s	-11.1%
⚡	WallTime	test_model_forecast[moirai-1.1]	1.5 s	1.3 s	+12.11%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing chore/release-v0.1.9 (2140e9d) with main (861ab65)}