fix(hermes): validate briefing state and event overlap

[furedea]

Summary

• treat calendar events as interval overlaps so ongoing multi-day events remain visible
• require newly surfaced research and technology identifiers to match the final report
• preserve prior digest state when atomic writes or read-back validation fail
• prohibit direct non-atomic state-write fallbacks

Test plan

• bats --print-output-on-failure tests/nix/hermes_secretary.bats
• lefthook pre-commit checks
• verify the secretary profile uses its profile root as terminal.cwd without the deprecated TERMINAL_CWD setting

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