fix: tighten uv version parser and platform-gate SYSTEMROOT in test client

[karthiknadig]

Summary

Addresses two unresolved Copilot review comments from merged PR #410.

Changes

• uv version parser: Major and minor components are now explicitly validated as purely numeric. Pre-release suffix (e.g., 0a4, 0rc1) is only allowed on the patch component (3rd+). Previously 3.12abc passed validation because the minor was the "last" component and only needed to start with a digit. Added test case for this scenario.

• SYSTEMROOT in test client: Platform-gated with #[cfg(windows)] and only set when std::env::var("SYSTEMROOT") succeeds. Previously used unwrap_or_default() which silently set it to empty string on non-Windows or when missing.

Follow-up to #410

[github-actions]

Test Coverage Report (Linux)

Metric	Value
Current Coverage	73.5%
Base Branch Coverage	73.5%
Delta	0% ➖

---

Coverage unchanged.

[github-actions]

Performance Report (Linux) ➖

Metric	PR (P50)	PR (P95)	Baseline (P50)	Delta	Change
Server Startup	1ms	1ms	1ms	0ms	0%
Full Refresh	96ms	139ms	77ms	19ms	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]

Performance Report (macOS)

Metric	PR (P50)	PR (P95)	Baseline (P50)	Delta
Server Startup	72ms	549ms	51ms	21ms
Full Refresh	146ms	31821ms	95ms	51ms

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	69.73%
Base Branch Coverage	69.73%
Delta	0% ➖

---

Coverage unchanged.

[github-actions]

Performance Report (Windows) ➖

Metric	PR (P50)	PR (P95)	Baseline (P50)	Delta	Change
Server Startup	13ms	16ms	9ms	4ms	44.4%
Full Refresh	201ms	410ms	148ms	53ms	35.8%

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)

[Copilot]

Pull request overview

This PR follows up on PR #410 by tightening input validation and improving cross-platform test isolation behavior.

Changes:

• Harden uv version parsing so major/minor components must be strictly numeric, and only the patch (3rd+) component may carry a pre-release suffix.
• Update the JSONRPC test client process spawn to only set SYSTEMROOT on Windows and only when it exists, avoiding empty-string injection on other platforms.

Show a summary per file

File	Description
crates/pet/tests/jsonrpc_client.rs	Refactors test server spawn to platform-gate SYSTEMROOT and avoid setting it to "" on non-Windows.
crates/pet-uv/src/lib.rs	Strengthens version component validation and adds a regression test for non-numeric 2-component minor versions.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 0