wet claude: startup warnings for CC version + Claude.app

[buildoak]

Summary

When wet claude starts, run two fast checks before handing over the terminal:

1. CC version mismatch

$ wet claude
⚠ CC 2.1.79 detected — wet validated against 2.1.78. Run 'wet check' if issues.
Starting proxy on :10000...

One claude --version exec + string compare. ~10ms.

2. Claude Desktop IPC warning

$ wet claude
⚠ Claude Desktop app running — CC may route through IPC, bypassing proxy.
  Quit Claude.app for reliable statusline. See: wet check
Starting proxy on :10000...

One pgrep -f "Claude.app". ~50ms.

Why

• CC auto-updates silently — version can change between sessions without the user knowing
• Claude.app IPC routing (CC ≥2.1.77) is the wet check: static CC compatibility diagnostics #1 foot-gun: proxy sees zero traffic, statusline blank, no error message
• Runtime warning at the moment it matters is higher value than any documentation

Implementation

In cli/shim.go, before spawning the CC child process:

1. Exec claude --version, parse, compare against compat.KnownStableCC
2. Exec pgrep -f "Claude.app", check exit code
3. Print yellow warnings to stderr if either check fails
4. Proceed normally — warnings are informational, never block startup

Dependencies

• Depends on compat: baked CC version constants package #2 (compat package)