feat: add full Cursor support

[AbsoluteMode]

What changed

• add Cursor as a first-class history source with consistent live-WAL reads, durable sanitized JSONL snapshots, incremental reconciliation, and raw grep/expand/step navigation
• add a native Cursor plugin bundle with MCP, commands, skills, recall agent, session-start indexing hook, and marketplace manifest
• harden embedding-space fingerprint reconciliation, source isolation, health reporting, and nested worktree scoping
• update English, Spanish, and Russian documentation and align plugin/package versions at 0.5.0

Why

Cursor previously had only shallow compatibility: its private SQLite rows were embedded without a durable transcript source, so deep navigation could not work reliably and schema changes could damage the last good index. This makes Cursor both a complete recall source and a native host for Session Recall.

Impact

Claude Code, Codex, and Cursor now share one semantic index. Cursor conversations remain navigable after Cursor closes, upgrades, or is removed, while raw normalized snapshots stay local.

Validation

• 353 passed, 3 deselected
• bundled-model smoke tests: 2 passed
• live read-only E2E against Cursor 3.14.7 using a fake local embedder
• Cursor plugin and marketplace manifests validated against the official schemas
• wheel and sdist build successfully; twine check, pip check, compileall, and git diff --check pass