feat: support WSL agent sessions on Windows

[dum3r]

Problem

On Windows, CodeDash can miss Linux-side agent history and running sessions that live inside WSL.

Typical setup:

• Windows host runs the dashboard
• real agent history is split between Windows home and \\wsl$\\<distro>\\home\\<user>
• active Claude/Codex processes may also be running inside the WSL distro

In that setup, the Windows dashboard currently treats WSL-side history/runtime as a blind spot.

Actual behavior

• sessions under WSL-side .claude / .codex are not ingested as first-class history on Windows
• running WSL agent processes are not surfaced as first-class Running entries on Windows
• if runtime association is weak, a process can end up attached to an unrelated latest session instead of being shown honestly as unresolved

Expected behavior

When CodeDash runs on Windows, it should be able to:

• discover WSL homes that actually contain .claude / .codex
• ingest those sessions into the normal session list / stats
• surface active WSL agent processes in Running
• prefer cmdline -> cwd-match -> explicit unresolved runtime instead of assigning an unrelated latest session
• disable Focus for runtimes where Windows cannot reliably focus the terminal

Proposed direction

• list WSL distros via wsl.exe
• resolve per-distro home and map it to \\wsl$\\...
• normalize path forms across \\?\\, Windows, /mnt/c/..., Linux, and \\wsl$\\...
• on Windows, scan only running distros for live WSL processes
• if a WSL runtime cannot be matched to a real session, show it as an explicit synthetic runtime entry instead of using fallback-latest

Local validation

I have a narrow branch based on v6.15.10 that implements this on Windows and validates:

• WSL home/session ingestion
• WSL live runtime detection
• disabled Focus for WSL runtime cards
• focused node --test coverage for WSL parsing / matching helpers

I am opening a PR from that branch next.