feat: add Tabnine CLI support

[balcsida]

Summary

• Add first-class Tabnine CLI integration (rtk init -g --tabnine and rtk hook tabnine)
• Tabnine CLI is a fork of Gemini CLI with identical BeforeTool hook wire format — reuses the existing Gemini hook processor via a shared run_gemini_format_hook() helper
• Installs hook script, AGENTS.md (Tabnine's default context file), and patches ~/.tabnine/agent/settings.json with the BeforeTool entry
• Full uninstall support via rtk init -g --tabnine --uninstall

Details

• Config dir: ~/.tabnine/agent/ (verified from installed Tabnine CLI binary and bundled source)
• Context file: AGENTS.md — confirmed as Tabnine's default contextFileName from tabnine.mjs source
• Hook format: identical to Gemini (tool_name + tool_input.command stdin, decision/hookSpecificOutput stdout)
• Dedicated HookCommands::Tabnine variant for clean logs and future divergence seam
• Added Tabnine detection to other_integration_installed in hook_check.rs

Test plan

• cargo fmt --all && cargo clippy --all-targets && cargo test --all — 1353 passed, 0 failed, zero new warnings
• 3 Tabnine-specific unit tests: rewriter parity, format handler signature, integration detection
• Live smoke test: echo '{"tool_name":"run_shell_command","tool_input":{"command":"git status"}}' | rtk hook tabnine → correct rewrite JSON
• Manual end-to-end: rtk init -g --tabnine --auto-patch → launched Tabnine CLI → shell commands rewritten through RTK
• CLI help shows --tabnine flag and rtk hook tabnine subcommand

[pszymkowiak]

[w] wshm · Automated triage by AI

📊 Automated PR Analysis

✨ Type	feature
🟡 Risk	medium

Summary

Adds first-class Tabnine CLI integration to RTK, including install/uninstall commands (rtk init -g --tabnine, rtk hook tabnine), hook script generation, AGENTS.md context file writing, and settings.json patching. Since Tabnine CLI is a Gemini CLI fork with an identical BeforeTool hook wire format, the implementation reuses the existing Gemini hook processor via a shared run_gemini_format_hook() helper.

Review Checklist

• Tests present
• Breaking change
• Docs updated

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Analyzed automatically by wshm · This is an automated analysis, not a human review.

[CLAassistant]

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