test: add unit tests for pet-windows-registry crate (Fixes #389)

[karthiknadig]

Add 4 new unit tests to pet-windows-registry (10 total, up from 6):

• try_from returns None for plain env without cache
• Sync from source with None cache clears shared state
• Sync is idempotent (double-sync produces same result)
• GlobalFiltered with Conda kind triggers sync

Fixes #389

[github-actions]

Performance Report (Linux) ✅

Metric	PR (P50)	PR (P95)	Baseline (P50)	Delta	Change
Server Startup	0ms	1ms	1ms	-1ms	-100.0%
Full Refresh	52ms	466ms	65ms	-13ms	-20.0%

Results based on 10 iterations. P50 = median, P95 = 95th percentile.

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Legend

• 🚀 Significant speedup (>100ms faster)
• ✅ Faster than baseline
• ➖ No significant change
• 🔺 Slower than baseline (>100ms)
• ⚠️ Significant slowdown (>500ms)

[github-actions]

Test Coverage Report (Linux)

Metric	Value
Current Coverage	80.0%
Base Branch Coverage	79.9%
Delta	.1% ✅

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Coverage increased! Great work!

[github-actions]

Performance Report (macOS)

Metric	PR (P50)	PR (P95)	Baseline (P50)	Delta
Server Startup	72ms	575ms	62ms	10ms
Full Refresh	144ms	29146ms	132ms	12ms

Results based on 10 iterations. P50 = median, P95 = 95th percentile.

---

Legend

• 🚀 Significant speedup (>100ms faster)
• ✅ Faster than baseline
• ➖ No significant change
• 🔺 Slower than baseline (>100ms)
• ⚠️ Significant slowdown (>500ms)

[github-actions]

Performance Report (Windows) ✅

Metric	PR (P50)	PR (P95)	Baseline (P50)	Delta	Change
Server Startup	10ms	13ms	9ms	1ms	11.1%
Full Refresh	145ms	345ms	153ms	-8ms	-5.2%

Results based on 10 iterations. P50 = median, P95 = 95th percentile.

---

Legend

• 🚀 Significant speedup (>100ms faster)
• ✅ Faster than baseline
• ➖ No significant change
• 🔺 Slower than baseline (>100ms)
• ⚠️ Significant slowdown (>500ms)

[github-actions]

Test Coverage Report (Windows)

Metric	Value
Current Coverage	77.03%
Base Branch Coverage	76.94%
Delta	0.09% ✅

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Coverage increased! Great work!