Rename detection event time fields in GraphQL (Closes #874)

[octoaide]

Summary

This PR implements the breaking GraphQL schema rename for ambiguous
detection event time fields as described in #874. It pins the
review-database dependency to commit 644db00 and updates schema
resolvers, field descriptions, fixtures, and tests to match the new
field names.

What changed

• Pinned review-database to commit 644db00 in Cargo.toml
• Renamed fields for multi-raw event-based detections:
  • startTime -> firstEventStartTime
  • endTime -> lastEventStartTime
    Affected event types: PortScan, MultiHostPortScan, ExternalDdos,
    FtpBruteForce, LdapBruteForce, RdpBruteForce, RepeatedHttpSessions
• Renamed fields for UnusualDestinationPattern:
  • startTime -> samplingWindowStartTime
  • endTime -> samplingWindowEndTime
• Updated GraphQL resolvers to reference the renamed database fields
• Updated field descriptions to document exact time semantics
• Updated representative fixtures and GraphQL event query tests
• Added schema introspection tests to ensure old fields are removed
• Updated CHANGELOG.md

Files touched (high level)

• Cargo.toml (dependency pin)
• src/graphql/event.rs and per-event resolvers (ftp, http, ldap, rdp,
  unusual_destination_pattern, conn, etc.)
• Tests and fixtures
• CHANGELOG.md

Breaking change

This is a breaking GraphQL schema change: clients that use the old
startTime/endTime fields must be updated to the new field names.

Testing notes / merge instructions

Local formatting, lint, and unit tests passed. I could not regenerate
Cargo.lock locally because GitHub DNS access prevented Cargo from
fetching the pinned review-database commit; as a result the lockfile was
not updated here. Please run cargo update -p review-database (or
allow CI to fetch and update the lockfile) before merging so the
lockfile contains the new reference.

Closes #874

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.33%. Comparing base (d762ada) to head (dc4ceda).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #909      +/-   ##
==========================================
+ Coverage   85.29%   85.33%   +0.04%     
==========================================
  Files          77       77              
  Lines       31067    31160      +93     
==========================================
+ Hits        26498    26591      +93     
  Misses       4569     4569              

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