[CTX-0079] fix(campaign): redact before truncation and bound campaign data

[Xuepoo]

Closes #139

Priority: P1 | Area: area:devtools | Labels: P1,fix,area:devtools | Milestone: v0.1.0 | RFC: OQ-004 | Task: CTX-0079

Summary

Implements redaction-before-truncation for semantic previews, bounds campaign data cardinality/output, constructs child environments from allowlist, sanitizes human output, clears session state on reconnect, and makes unsupported trace/control paths explicit.

Changes

• Rust (devtools-client): Enhanced redaction with normalization, separator extraction, multi-pass redaction logic
• TypeScript (campaign.ts): Bounded output/envelopes/reports, allowlist-based child environment construction, session state management
• TypeScript (redaction.ts): Redact-before-truncate for semantic previews
• Tests: Synthetic secret/control sentinels, fake spawn environment, oversized arrays, reconnect, bounded cancellation

Testing

• All quality gates passed (just check)
• 493 TypeScript tests passed
• 85 Rust tests passed
• Synthetic fixtures for redaction validation

Review

Awaiting CI and independent review.