[Bug] `/insights` command missing trailing backslash on Windows path construction

**Bug Description**
The /insights on windows isnt including the trailing / after the user profile location (see after jagbe) eg. C:\Users\jagbe.claude\usage-data\report-2026-07-26-084334.html vs C:\Users\jagbe\.claude\usage-data\report-2026-07-26-084334.html. This happened on another window pc too using the terminal.

**Environment Info**
- Platform: win32
- Terminal: WarpTerminal
- Version: 2.1.219
- Feedback ID: 12a9a429-0067-4b2b-a208-a5d06465b7f2

**Errors**
```json
[{"error":"TelemetrySafeError: VirtualMessageList: itemKeys/messages length desync (keys=233 messages=231 range=[166,233))\n at $zb (B:/~BUN/root/src/entrypoints/cli.js:21739:8188)\n at Ahf (B:/~BUN/root/src/entrypoints/cli.js:21739:1103)\n at no (B:/~BUN/root/src/entrypoints/cli.js:2061:21369)\n at DA (B:/~BUN/root/src/entrypoints/cli.js:2061:40466)\n at q3 (B:/~BUN/root/src/entrypoints/cli.js:2061:51400)\n at Pne (B:/~BUN/root/src/entrypoints/cli.js:2061:89060)\n at ULe (B:/~BUN/root/src/entrypoints/cli.js:2061:88007)\n at Wge (B:/~BUN/root/src/entrypoints/cli.js:2061:87827)\n at nQ (B:/~BUN/root/src/entrypoints/cli.js:2061:84091)\n at Rt (B:/~BUN/root/src/entrypoints/cli.js:2061:6668)","timestamp":"2026-07-25T05:33:00.293Z"}]
```

Start by locating the /insights command and its Windows path-construction entry point. Reproduce the command on win32 or inspect the generated usage-data report path, then verify that the user profile and .claude segments remain separated by a path delimiter and that the report opens at the expected location.

Written by the indexing model from the issue text.