v0.2.0 — UI cards + four new git tools

v0.2.0

UI cards + four new tools — the tool family grows from five to nine tools, and git_diff / git_show now render as real UI cards in the Web GUI.

✨ New tools

• git_branch — list / create / checkout / delete branches. Listing returns structured branches[] (name / current / upstream); deletes require force: true to drop an unmerged branch.
• git_show — inspect a commit (metadata + patch, or a numeric stat summary) or a single file's content at any revision (rev:path).
• git_restore — discard working-tree changes or unstage paths (staged: true), reporting the exact restored[] list. Destructive; deployment policy can gate it via tools/pre-execute.
• git_merge — merge a branch/commit (--no-ff, custom message, abort supported). A merge conflict is a domain outcome: it returns the conflicting files (via porcelain v2) instead of failing.

🎨 UI cards

• git_diff and git_show (commit mode) project replayable diff cards through output.presentationMeta — a pure unified-diff parser turns the diff text into per-file oldText/newText pairs that survive session-log replay.
• git_show (file mode) renders a line-numbered read card.
• All nine tools get presentCall / presentResult; git_diff / git_add attach file locations for editor follow-along.

🔗 Compatibility

• Requires git ≥ 2.23 (now that git restore is used).
• Still tested against DeepSeek Harness 0.1.0-rc.6.

✅ Quality

• Test suite grows to 53 vitest tests (6 unified-diff parser, 19 new integration tests) — all passing, plus full CI and real-harness verification.