fix: report a reasoning_effort the adapter cannot carry

[yoke-yoke]

Closes #11.

What

readMuseSettings now logs when reasoning_effort holds a value outside
EFFORT_LEVELS, naming the supported values. The fallback itself is unchanged:
the session still runs at the default.

Why here rather than in defaultSessionConfig

readMuseSettings already owns this job. It reports its two other failure modes,
a missing file and a non-object document, and it is the only one of the two that
already receives a logger. Every call site is
defaultSessionConfig(readMuseSettings(env, this.logger)), so nothing has to be
rethreaded.

One thing to call out

muse-settings.ts now imports from config-options.ts, which imports
MuseSettings back. That reverse edge is type-only and TypeScript elides it, so
the emitted dist/config-options.js keeps a single import and there is no runtime
cycle. If you would rather not carry the compile-time edge at all, say so and I
will move EFFORT_LEVELS and isReasoningEffort into a leaf module that both
files import.

Verified

• the new test fails without the change, on the missing log line
• npx vitest run src/tests/muse-settings.test.ts src/tests/config-options.test.ts: 14 passed
• npm run build: clean
• npm run check: clean

One caveat, stated plainly: npm run test:unit is unstable on my machine. Failures
are timing based (Matcher did not succeed in time, write EPIPE) and differ from
run to run, between 1 and 10 files, never touching the two files this change
concerns. I could not get a stable full-suite baseline to compare against.

[yoke-yoke]

One correction to the premise in this PR's commit message, now filed as #13: max is not a CLI-only level that the adapter has no wire type for. It is in the protocol as of @muse-code/sdk 1.3.0, published one day after 0.6.1; the adapter simply pins 0.1.1.

That does not change this patch. Whatever EFFORT_LEVELS ends up containing, a value outside it is still replaced by the default with nothing logged, and that is what this fixes. I will reword the commit message if you prefer it to match.