fix: #22 deserialization for CBOR floats

[gpeacock]

PrefetchedDeserializer, used when deserializing Option, only handled booleans for CBOR major type 7 (simple/float) and errored on floats (info 25/26/27) and undefined. This broke any struct with an optional float field, e.g. Option shape dimensions.

Changes in this pull request

Give a narrative description of what has been changed.

Checklist

• This PR represents a single feature, fix, or change.
• All applicable changes have been documented.
• Any TO DO items (or similar) have been entered as GitHub issues and the link to that issue has been included in a comment.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 66.16%. Comparing base (3fd0162) to head (d881a73).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/decoder.rs	0.00%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #25      +/-   ##
==========================================
- Coverage   66.58%   66.16%   -0.43%     
==========================================
  Files           6        6              
  Lines        1721     1732      +11     
==========================================
  Hits         1146     1146              
- Misses        575      586      +11     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[codspeed-hq]

Merging this PR will improve performance by 10.63%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
✅ 29 untouched benchmarks

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	decode_vec_1000_ints	53.5 µs	48.4 µs	+10.63%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing gpeacock/fix-issue-22-option-float (d881a73) with main (3fd0162)}

[gpeacock]

tests are in integration and not caught by code coverage yet.