V1 [TEST] Add fuzz targets for query parser and HTTP handlers

[austin-barrington]

Context

The repository does not use fuzz testing or property-based testing. The query parser (timeseriesql) and HTTP request handlers are natural targets for fuzzing.

Deliverables

• Add cargo-fuzz targets for:
  • Line protocol parser — feed random byte sequences, check for panics
  • Query parser — feed random strings, check for panics
  • JSON write endpoint — feed random JSON, check for 5xx
  • Config file parser — feed random TOML, check for panics
• Setup fuzz CI job (not required, but document how to run fuzz targets)
• Fix any panics discovered during fuzz target development

References

• src/timeseriesql/ — query parser
• src/adapters/http/write.rs — line protocol and JSON write handlers
• cargo-fuzz book: https://rust-fuzz.github.io/book/

Priority

P2 — Security hardening, test coverage