fix: replace blocking time.sleep with asyncio.sleep in async context (closes #125)

[geored]

Root Cause

time.sleep(2) in _setup_port_forward (line 520) is a synchronous C-level blocking call inside an async def function. It freezes the entire asyncio event loop for 2 seconds, stalling all concurrent MCP tool requests during local development port-forwarding.

Fix

Approach 2 (Defensive) — selected from 3 simulated approaches:

1. Replaced time.sleep(2) with await asyncio.sleep(2) — yields control to the event loop during the wait
2. Added import asyncio (was not previously imported)
3. Removed import time (verified: only usage in file was this sleep call)
4. Added explanatory comment documenting the async constraint

Why This Approach

• Approach 1 (Minimal) rejected: leaves dead import time and no documentation
• Approach 3 (Refactor) rejected: converting subprocess.Popen to asyncio.create_subprocess_exec breaks stop_port_forward (sync method calling .wait(timeout=5)) and the type annotation at line 93

Investigation Trace

1. Confirmed import time at line 19, asyncio NOT imported
2. Found time.sleep(2) at line 520 inside async def _setup_port_forward
3. Searched all time. usages — only one (line 520). Lines 1652/1660/1667 use datetime, not time
4. Verified removing import time is safe
5. Verified subprocess import must stay (15 usages across the file)

Closes #125