fix: name function_logs and event_message in the ClickHouse query_logs hint

[Rjabov]

Closes #375

Problem

On hosted projects get_logs is hidden, so query_logs is the only logs tool. Its ClickHouse
hint names function_edge_logs but not function_logs, and tells the model to read
log_attributes['<key>'] without mentioning event_message. log_attributes holds only
metadata (level, execution_id, request_id); the log line text lives solely in event_message.

The result is a model that reaches the right table, reads the wrong column, and tells the user
their output was never stored:

"The console.log output from your order-sync edge function is not being stored in the
queryable project logs."

Change

Names both Edge Function sources, and states that event_message carries the log line while
log_attributes carries metadata. Additive prose only; the select distinct source from logs
escape hatch is unchanged, and the BigQuery hint is untouched (self-hosted Logflare does not
serve function_logs, and its not.toContain assertion still passes).

Evidence

32-run matrix against a live project (4 models × 2 prompts × 2 reasoning levels × 2 builds),
test function returning HTTP 200 on every call while logging an error line, graded on whether
the answer contains the actual error text.

• Naming the source alone: 14 comparable cells, zero changed. Models already reach
  function_logs unaided (Haiku did so in 7/7 runs on both builds).
• Adding event_message: the 5 previously-failing cells, 2 replicates each, 10/10 pass,
  median 1.5 queries versus a median of 4 while failing.

Local: pnpm run build, 215/215 unit tests, pnpm typecheck clean,
npx @biomejs/biome@1.9.4 ci . clean (89 files).

Two caveats: an earlier version of this description presented a scripted client with hardcoded
SQL as though an agent had chosen the query, which overstated it. And I retested only
previously-failing cells, so I have not shown the new wording leaves passing cells alone.

Published metadata

This edits a .describe() string, in the frozen-fields list. Purely additive, no schema shape
or optionality change, so it should fit the expand step, but flagging in case it should be
folded into the next plugin submission.