feat(ide): complete Phase 2 IDE integrations for all major editors

[yesudeep]

VS Code Extension (v0.2.0):

• Add status bar indicator showing LSP connection state
• Add format on save configuration (dotprompt.formatOnSave)
• Add commands: Format Document, Restart LSP, Show Output
• Improve error handling with actionable dialogs

JetBrains Plugin (v0.2.0):

• Add 18 live templates (role, system, user, if, each, json, etc.)
• Add settings UI at Settings → Languages & Frameworks → Dotprompt
• Add DotpromptSettings for persistent configuration
• Update PromptlyServerFactory to use configured promptly path

Neovim/Vim:

• Add lua/dotprompt/init.lua module for easy LSP setup
• Add format on save and default keymaps (f, K, gd, gr)
• Add Tree-sitter integration docs to README

Emacs (v0.3.0):

• Add dotprompt-format-buffer command (C-c C-f)
• Add dotprompt-format-on-save option
• Add Doom Emacs, Spacemacs, straight.el config examples

Tree-sitter Grammar:

• Add test corpus with 8 test cases
• Add integration examples for nvim-treesitter, Helix, Zed