feat(otel): add getRoute callback so adapters can resolve http.route

[spokodev]

Closes #1914.

@hono/otel overwrote the http.route attribute on the active span at finalize time with the matched Hono pattern (e.g. /rpc/*), even when a downstream adapter resolved a more specific operation name (e.g. /rpc/user/getProfile) during request handling. The same Hono pattern was reported as the http.route attribute of the http.server.request.duration metric, so per-operation latency collapsed into the pattern bucket.

This PR adds a getRoute(c) config callback. When it returns a non-empty string the value is used at finalize for both the span attribute and the metric attribute. When it returns undefined, an empty string, or throws, the middleware falls back to routePath(c), so the existing behavior is preserved when the callback is not provided.

Typical adapter usage:

app.use(
  httpInstrumentationMiddleware({
    tracerProvider,
    getRoute: (c) => c.get('rpc.route'),
  })
)

Verification:

• 5 new tests in packages/otel/src/index.test.ts:
  • span http.route reflects the getRoute return value
  • metric http.route reflects the getRoute return value
  • getRoute returning undefined falls back to routePath(c)
  • getRoute returning an empty string falls back to routePath(c)
  • getRoute throwing falls back to routePath(c)
• RED baseline confirmed: reverting index.ts + types.ts to main makes the two positive tests fail; applying the fix turns them green
• yarn test --run for @hono/otel: 27 / 27 (22 existing + 5 new)
• yarn typecheck clean
• yarn turbo run lint --filter=@hono/otel clean
• yarn format reports All matched files use Prettier code style!
• Changeset added at .changeset/otel-get-route-callback.md (@hono/otel: minor)

Out of scope:

• The initial attributes passed to tracer.startActiveSpan still use routePath(c), because getRoute may rely on context state that downstream middleware writes after the span is started. The finalize step updates the attribute to the resolved value so the exported span and the metric agree.

[changeset-bot]

🦋 Changeset detected

Latest commit: 4cc351b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@hono/otel	Minor

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