TRACES: | DR-204 | UT-201
The Rust half of the app logs through the `log` crate behind `env_logger`,
with `LevelFilter::Info` by default and `RUST_LOG` to turn the volume up
without a rebuild. The frontend had no equivalent at all: every
`console.log` written during development shipped to end users.
`createLogger(scope)` gives the frontend the same shape:
- four levels (debug/info/warn/error), gated by severity;
- verbose in dev, `warn` in production — warn and error are never gated
away, because a silent failure in a networked media client is worse to
support than a noisy console;
- `localStorage["jellytau:logLevel"]`, read once at init, as the
`RUST_LOG` equivalent so a user can gather verbose logs for a bug
report without a rebuild. Guarded for SSR and for webviews where
storage access throws;
- the scope replaces the hand-written `"[Scope] …"` prefixes;
- a thin pass-through: arguments reach `console.*` untouched and by
reference, and `console` is resolved at call time so devtools
overrides and test spies still see everything.
