#3941 refactor(service): retire eve's session stream, which nothing follows any more

A small follow-up to #3937, stacked on it. The coordinator asked for it.

#3937 moved the voice brain off eve's session stream and onto the task conversation's mark over Neon Realtime. That left EveSessions.stream with no caller, so this PR removes it:

• the stream method on EveSessions, with its reader (streamFromEve, readStreamLine, streamedEvent, EveStreamEvent, STREAM_FROM_TAIL)
• the two eve-sessions.test.ts tests for that reader, and their streaming fixture
• the empty stream on every fake eve: coder-host/host.ts's, and those in eight test files

Behaviour doesn't change: nothing read the stream after #3937.

Checks run locally

pnpm check:affected gets OOM-killed in the sandbox, so I ran its pieces one at a time:

• repository-checks.sh, biome check ., oxlint, knip
• discarded-effect (with a larger heap)
• tsc for service
• vitest for brain-host, coder-start, coding-agents-app, automations, agent-wakes, and voice (310 tests)

What to check by hand

Nothing: there's no visible change.

Made with Luke