fix: Cleanup pass — 7 audit findings

[strawgate]

Summary

Fixes 7 findings from the reference-doc-guided codebase audit. All verified against current master.

Issue	Fix	Severity
#125	StreamingBuilder: move has_int/has_float after parse success	HIGH — ghost null columns
#128	Add 30s HTTP timeout to OtlpSink and JsonLinesSink	MEDIUM — hung endpoint blocks pipeline
#129	FanOut: try all sinks before returning error	MEDIUM — first failure was skipping remaining sinks
#130	Store and reuse ureq::Agent for connection pooling	MEDIUM — was creating new TCP connections per batch
#132	RawParser: escape control chars 0x00-0x1F per RFC 8259	LOW — invalid JSON output
#134	Replace assert! with Result in add_enrichment_table	LOW — runtime panic on bad config

Not in this PR (bigger changes):

• bug: Data loss on file rotation — old fd dropped without draining #123 data loss on rotation (needs careful file I/O)
• bug: CRI parser drops partial lines at chunk boundaries #124 CRI partial lines (needs buffer management)
• perf: SqlTransform creates new tokio runtime per batch #126 SqlTransform runtime per batch (Phase 2 architecture)
• perf: zstd::bulk::compress allocates new CCtx per call #127 zstd context reuse (needs compress.rs refactor)
• fix: Leaked tokio runtime via std::mem::forget in main.rs #131 runtime leak (Phase 3 async migration)

Test plan

• cargo clippy -- -D warnings clean
• cargo test all pass
• cargo fmt --check clean

Closes #125, #128, #129, #130, #132, #134.

🤖 Generated with Claude Code

[coderabbitai]

Caution

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Pull request was closed or merged during review

Walkthrough

Changes span multiple crates addressing encoding, HTTP efficiency, error handling, and validation. JSON output now escapes newlines and control characters per RFC 8259. Numeric parsing flags are set only after successful validation, preventing ghost null columns. HTTP sinks now reuse persistent agents with 30-second timeouts rather than creating requests through global constructors. Multi-sink error handling defers failures to complete all operations before returning the first error. Enrichment table validation transitions from panics to explicit Result returns with checks for reserved names and duplicates.

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	PR addresses #125 by moving has_int/has_float flag assignment to after parse success, preventing ghost null columns.
Out of Scope Changes check	✅ Passed	Changes in fanout.rs, json_lines.rs, otlp_sink.rs, format.rs, and lib.rs address audit findings #128–#134 as documented.

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