feat: convert to workspace with native plugin architecture

BREAKING: Restructure from monolithic binary to modular plugin ecosystem

Architecture changes:
- Convert to Cargo workspace with crates/ directory
- Create owlry-plugin-api crate with ABI-stable interface (abi_stable)
- Move core binary to crates/owlry/
- Extract providers to native plugin crates (13 plugins)
- Add owlry-lua crate for Lua plugin runtime

Plugin system:
- Plugins loaded from /usr/lib/owlry/plugins/*.so
- Widget providers refresh automatically (universal, not hardcoded)
- Per-plugin config via [plugins.<name>] sections in config.toml
- Backwards compatible with [providers] config format

New features:
- just install-local: build and install core + all plugins
- Plugin config: weather and pomodoro read from [plugins.*]
- HostAPI for plugins: notifications, logging

Documentation:
- Update README with new package structure
- Add docs/PLUGINS.md with all plugin documentation
- Add docs/PLUGIN_DEVELOPMENT.md

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

crates/owlry-lua/src/api/mod.rs

@@ -0,0 +1,52 @@
+//! Lua API implementations for plugins
+//!
+//! This module provides the `owlry` global table and its submodules
+//! that plugins can use to interact with owlry.
+
+mod provider;
+mod utils;
+
+use mlua::{Lua, Result as LuaResult};
+use owlry_plugin_api::PluginItem;
+
+use crate::loader::ProviderRegistration;
+
+/// Register all owlry APIs in the Lua runtime
+pub fn register_apis(lua: &Lua, plugin_dir: &std::path::Path, plugin_id: &str) -> LuaResult<()> {
+    let globals = lua.globals();
+
+    // Create the main owlry table
+    let owlry = lua.create_table()?;
+
+    // Register utility APIs (log, path, fs, json)
+    utils::register_log_api(lua, &owlry)?;
+    utils::register_path_api(lua, &owlry, plugin_dir)?;
+    utils::register_fs_api(lua, &owlry, plugin_dir)?;
+    utils::register_json_api(lua, &owlry)?;
+
+    // Register provider API
+    provider::register_provider_api(lua, &owlry)?;
+
+    // Set owlry as global
+    globals.set("owlry", owlry)?;
+
+    // Suppress unused warnings
+    let _ = plugin_id;
+
+    Ok(())
+}
+
+/// Get provider registrations from the Lua runtime
+pub fn get_provider_registrations(lua: &Lua) -> LuaResult<Vec<ProviderRegistration>> {
+    provider::get_registrations(lua)
+}
+
+/// Call a provider's refresh function
+pub fn call_refresh(lua: &Lua, provider_name: &str) -> LuaResult<Vec<PluginItem>> {
+    provider::call_refresh(lua, provider_name)
+}
+
+/// Call a provider's query function
+pub fn call_query(lua: &Lua, provider_name: &str, query: &str) -> LuaResult<Vec<PluginItem>> {
+    provider::call_query(lua, provider_name, query)
+}