Strava connector (mcp.strava.com/mcp) missing gear_id

### What happened?

list_activities (and likely get_activity_performance) never returns the gear_id field for any activity, even though the tool's own description says it should be included, and even when gear is correctly tagged on the activity in Strava itself. Confirmed by tagging a bike on an activity in Strava directly — the tag shows correctly on strava.com, but the MCP's list_activities response for that activity still omits gear_id entirely.

### What did you expect to happen?

gear_id should be populated when an activity has gear tagged in Strava.

### Steps to reproduce

Steps to reproduce:

In Strava, tag an activity with a gear item (e.g. a bike) via the activity's Edit screen so it's correctly linked in Strava's gear field.
In Claude, call the Strava MCP's list_activities tool (or get_activity_performance) with include_tags: true.
Observe the returned JSON for that activity.

### Area

Tool Discovery / Invocation

### MCP Server (if applicable)

mcp.strava.com/mcp

### Error messages or logs

```shell
No error thrown — call returns successfully but silently omits the field.
Raw response for that activity:

json
{
"id": "19718464758",
"name": "Mountain Bike Ride",
"description": "Bike: Trail",
"sport_type": "MountainBikeRide",
"start_local": "2026-08-12T18:00:14",
"is_trainer": false,
"summary": {
"distance": 15994.4,
"moving_time": 4510,
"elapsed_time": 4969,
"elevation_gain": 140,
"avg_speed": 3.546430155210643,
"max_speed": 8,
"relative_effort": 95,
"total_calories": 622,
"kudos_count": 1,
"achievement_count": 2,
"pr_count": 2
}
}

Note: no gear_id, no activity_tags, no is_commute — all three were requested via include_tags: true and all three are missing.
```

### Additional context

_No response_

Start by locating the Strava MCP handlers for list_activities and get_activity_performance, then trace how include_tags: true is mapped into the returned activity fields. Reproduce with an activity that has gear in Strava and verify that gear_id, activity_tags, and is_commute are returned when requested, without changing the successful response behavior for activities lacking those fields.

Vom Indexierungsmodell aus dem Issue-Text verfasst.