pstack: bump version to 0.2.0

[poteto]

Summary

Bumps the pstack plugin version from 0.1.0 to 0.2.0.

Since 0.1.0, this release adds:

• New playbooks: refactoring, session pickup, trace forensics, plus figure-it-out and show-me-your-work skills.
• New principle: build-the-lever.
• README refresh: skills table, examples section, and the playbooks rendered as a table.

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Note

Low Risk
Single-field version bump in plugin metadata with no runtime or security impact.

Overview
Bumps the pstack Cursor plugin manifest version from 0.1.0 to 0.2.0 in pstack/.cursor-plugin/plugin.json. No other files or metadata change in this diff.

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