fix: support natural day span queries

[konard]

Summary

• parse ordinal month dates such as 8th august
• accept the optional of preposition in dates such as 8th of august
• support days between <date> and <date> and days to <date> as signed day-count queries
• route natural queries through the existing datetime subtraction and duration conversion behavior

Reproduction

Before this change, all four reported expressions failed to parse:

days between 8th august and now
((8th august - now) as days)
8th of august - now
days to 8th of august

The regression suite covers every reported expression and verifies the deterministic query days between 8th august 2026 and 24th of july 2026 returns 15 days.

Verification

• cargo fmt --all -- --check
• cargo clippy --all-targets --all-features
• node scripts/check-file-size.mjs
• node --test scripts/*.test.mjs
• cargo test --all-features --verbose
• cargo test --doc --verbose
• cargo build --release --verbose
• cargo package --list --allow-dirty
• wasm-pack build --target web --out-dir web/public/pkg
• npx tsc --noEmit
• npm test (229 tests)
• npm run build

Fixes #207
Fixes #203
Fixes #204
Fixes #205
Fixes #206

[konard]

Working session summary

Implemented and finalized the fix in PR #208.

• Added support for ordinal dates with optional of.
• Added days between … and … and days to … expressions.
• Added regression tests covering all four sub-issues.
• Added the required changelog fragment.
• Full Rust, WASM, TypeScript, web, formatting, lint, and packaging checks pass.
• Fresh GitHub CI is fully green.
• PR is ready for review, mergeable, and the working tree is clean.

Commit: 298f1b12900d365f3c77117d1db09172c251033f

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This summary was automatically extracted from the AI working session output.

[konard]

🤖 Solution Draft Log

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💰 Cost estimation:

• Model: GPT-5.6 Sol
• Provider: OpenAI
• Public pricing estimate: $8.190328

📊 Context and tokens usage:

• 207.9K / 200K (104%) input tokens, 17.5K / 128K (14%) output tokens

Total: (207.9K + 5.3M cached) input tokens, 17.5K output tokens, $8.190328 cost

🤖 Models used:

• Tool: OpenAI Codex
• Requested: gpt-5.6-sol
• Thinking level: medium (~15999 tokens)
• Model: GPT 5.6 Sol (gpt-5.6-sol)

📎 Log file uploaded as Gist (1949KB)

• View complete solution draft log

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Now working session is ended, feel free to review and add any feedback on the solution draft.

[konard]

✅ Ready to merge

This pull request is now ready to be merged:

• All CI checks have passed
• No merge conflicts
• No pending changes

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