Custom connector: path segment in URL is uppercased after saving, and stale resource metadata is used for OAuth discovery

### What happened?

**Summary**

When adding a custom MCP connector whose URL contains a lowercase path segment (in our case, a tenant identifier), the value is not preserved as entered. After saving, the connector's stored/displayed URL shows that segment uppercased, even though it was typed in lowercase and never edited.

**Steps to reproduce**

1. Open "Add custom connector."
2. Name: `Seismic`
3. URL: `https://mcp.seismic.com/v1/tenants/fico` (lowercase `fico`)
4. Click "Add."
5. Reopen the connector's details.

**Expected behavior**

The URL in "Connector details" should exactly match what was entered: `https://mcp.seismic.com/v1/tenants/fico`.

**Actual behavior**

"Connector details" shows `https://mcp.seismic.com/v1/tenants/FICO` — the tenant segment has been uppercased. Screenshots attached:

- "Add custom connector" dialog with URL entered as `.../tenants/fico`
- "Connector details" for the same connector immediately after, showing `.../tenants/FICO`

**Why this isn't just a display bug**

We traced this further with server-side request logs on our end:

- This is happening on customer org only, and does not reproduce on other org.
- Also happening for this one single tenant path only (`fico`). The connector saved as typed, for other tenant paths.
- Additionally when trying to connect, Claude does a lookup on wrong metadata endpoint `https://mcp.seismic.com/.well-known/oauth-protected-resource` instead of expected `https://mcp.seismic.com/.well-known/oauth-protected-resource/v1/tenants/fico`

This pattern suggests the connector setup isn't always treating the freshly entered URL as authoritative. It looks like it's resolving to a pre-existing record for that resource (matched on something looser than the exact path/case) and reusing that record's stored data, including a different case and different discovery metadata, instead of the value the user just entered. We believe the uppercase display and the wrong discovery endpoint are two symptoms of the same underlying issue, not separate bugs.

**Impact**

This blocked a customer from connecting to our MCP server via a tenant-specific URL.

**Environment**

- Claude.ai custom connector ("Add custom connector" flow)
- MCP server: `https://mcp.seismic.com/v1/tenants/{tenant}`

Let me know if you need any other details for investigation.

### What did you expect to happen?

The connector is saved with the endpoint as typed. It should not capitalize or modify any part of endpoint. Once saved, it should follow the proper metadata discovery lookup as per the protocol.

### Steps to reproduce

This is reproducing on customer org only for multiple Claude Admins.
It doesn't reproduce on our/other orgs or personal acc.

### Area

MCP Connector (adding/managing servers)

### MCP Server (if applicable)

https://mcp.seismic.com/v1/tenants/fico

### Error messages or logs

```shell

```

### Additional context

_No response_