Add bounded offline PCAP analysis to Traffic Explorer

[Adam-Ghanem]

Summary

• add a PCAP/PCAPNG file picker directly to Traffic Explorer
• call the existing authenticated /api/traffic/offline/analyze endpoint with raw capture bytes
• require a dedicated explicit authorization confirmation for offline evidence
• expose bounded packet and flow limits and reuse the current protocol/IP filters
• render offline results through the existing traffic analysis view
• keep offline analysis usable without live sensor NET_RAW privileges
• retain metadata-only behavior and explicitly report that raw payload bytes are not retained

Tests

• extend frontend contract coverage for the offline-analysis UI wiring, authorization control, bounded limits, raw upload content type, endpoint construction, and result rendering

Safety

This only analyzes capture files the operator owns or is authorized to assess. It does not add replay, injection, payload search, credential extraction, or active scanning behavior.