Floe v0.4.0

What's Changed

• feat(lineage): add circuit breaker and retry to OpenLineage observer by @malon64 in #299
• test(pii): add DataFrame-level tests for all PII masking strategies by @malon64 in #300
• [codex] Harden remote incremental state by @malon64 in #297
• test(unity): harden Unity Catalog — fix token expansion footgun and add HTTP interaction tests by @malon64 in #301
• refactor(core): v0.4.0 P0+P1 hardening — enum severity, thiserror, dead-code removal, merge deduplication by @malon64 in #302
• refactor(sink): SinkFormat trait — unified write + seed + data-driven validation by @malon64 in #303
• refactor(state): eliminate duplicated load/persist/claim patterns by @malon64 in #304
• chore: clean example dir and add context/ for agent/contributor orientation by @malon64 in #305
• fix(manifest): wire k8s runner fields from profile into generated manifest by @malon64 in #306
• chore: bump all crates to v0.4.0 by @malon64 in #307
• fix: update version to 0.4.0 in pyproject.toml by @malon64 in #308

Full Changelog: v0.3.10...v0.4.0