feat: bug fixes, lazy.nvim-style controls, auto-update checking, repo polish

Phase 1 - Bug fixes:
- Fix extmark rendering in text.lua (table vs string hl handling)
- Fix timer leak: WinClosed autocmd now triggers view.close()
- Add GOBIN/GOPATH/~/go/bin awareness to is_installed() and new bin_path()
- Reject update_all() while tasks running (race condition fix)
- Implement _toggle_details with full binary info expansion

Phase 2 - Lazy.nvim-style controls:
- U = Update all, u = update cursor binary
- I = Install all missing, i = install cursor binary
- x = Abort, CR = toggle details, q/Esc = close
- Line-to-binary mapping for cursor-aware actions

Phase 3 - Auto-update checking:
- New checker module with go list/go version -m integration
- auto_check config option (daily/weekly/custom frequency)
- Persistent state in stdpath('data')/glaze/state.json
- :GlazeCheck command for manual checks
- Update indicators in UI (version info + arrows)

Phase 4 - Repo polish:
- MIT LICENSE file
- Doughnut-themed README with badges and Why Glaze? section
- Updated help docs with all new features/keybinds/API

lua/glaze/runner.lua

@@ -139,6 +139,12 @@ end
 local function run(names, mode)
   local glaze = require("glaze")
 
+  -- Reject if already running (race condition fix)
+  if M._running then
+    vim.notify("Glaze: tasks already running. Wait or abort first.", vim.log.levels.WARN)
+    return
+  end
+
   -- Check for Go
   local go_check = glaze.config.go_cmd[1]
   if vim.fn.executable(go_check) ~= 1 then