feat: add isolated projects and capture migration workflows

[LocNguyenHuu]

Summary

Promote the completed Project and investigation workflows from develop to main.

• add isolated Project workspaces with durable switching, per-Project History and settings, protected source ownership, and configuration-only transfer
• add bounded capture migration for PCAP, PCAPNG, gzip, and observed TCP Viewer schema-1 archives, with timestamp integrity and Linux SLL/SLL2 interoperability
• add Session Expressions, explicit scope/return/reset behavior, aggregate drill-downs, and evidence navigation while preserving the native Rockxy-aligned workspace
• update architecture, privacy, protocol support, migration, usage, and UI documentation

Validation

• xcodebuild -project Tracexy.xcodeproj -scheme Tracexy -destination 'platform=macOS' test -only-testing:TracexyTests — 1,376 test definitions and 1,446 expanded cases passed, with 0 failures and 0 skips on the exact develop tree
• swiftlint lint --strict — 0 violations across 182 files
• swiftformat --lint . — 0 of 334 files require formatting
• git diff --check origin/main...origin/develop
• conflict-free merge-tree simulation against the current main
• native TCP Viewer archive import and Session Expression valid/invalid lifecycle replay

Safety Checklist

• Targets main from develop.
• Includes regression coverage and updated documentation for user-facing behavior.
• Preserves capture/helper/XPC trust boundaries and local-by-default data handling.
• Contains no credentials, signing files, machine-specific paths, raw captures, or private configuration.

Notes

main contains the published 0.6.0 release metadata. The branches have diverged since that release; the verified merge result preserves those metadata changes without conflicts.

The Public Safety full-history check reports six already-published Stephen-authored commit email metadata entries reachable from develop; the current source tree scan is clean. This PR does not rewrite published Git history.

The unsigned GitHub macOS runner passes 1,374 of 1,376 unit test definitions and all four UI tests. Two audit-token identity tests cannot obtain a signing identifier from the unsigned test host; the same develop tree passes all 1,376 definitions and 1,446 expanded cases in the signed local run recorded above.