Adds previously-missing documentation for logging configuration (fixes
#2498) and a couple of related fixes to the doc site.
- **docs: expand logging settings section in configurations** — the page
only listed the logging flags as a table without any explanation. Adds
usage details: default behavior, `--console-log-level` /
`ET_CONSOLE_LOG_LEVEL`, `RUST_LOG` per-target filters, enabling file
logging with a non-`off` `--file-log-level` plus the optional
`--file-log-dir`/`--file-log-size`/`--file-log-count` knobs, runtime
adjustment via `easytier-cli logger`, and why logging is a process-level
option that cannot go in the `-c` config file. Both zh and en.
- **fix: dev-server white screen** — vite dev serves `node_modules`
sources as-is unless prebundled; mermaid's named import from the
pure-CJS `@braintree/sanitize-url` then fails in the browser and blanks
the whole page. Add `optimizeDeps.include: ['mermaid']` so the dev
server prebundles it (rollup build was already fine).
- **docs(configurations): flatten section structure** — the single h2
"Basic Settings" wrapped every parameter group as h3, so the on-page
outline only showed one entry. Promote each group to its own h2 and
enable `outline: deep` so the logging sub-topics also appear. Both zh
and en.
Myqfeng