When the user triggers SQL execution via shortcut/toolbar/context-menu
without a manual selection, a floating picker now surfaces the available
execution targets:
- "Current SQL" — the statement at the cursor
- "All SQL" — the entire editor content
Each candidate is highlighted as a preview decoration in the editor as
the user navigates the picker with arrow keys. Only a single entry is
shown when the cursor statement equals the full document.
前端 SQL 范围解析器 (sqlStatementRanges.ts) 按分号拆分语句，同时跳过
字符串、引号标识符、注释和美元引用体中的分隔符，与后端 dbx-core splitter
逻辑一致。选取器支持键盘导航、鼠标悬停高亮、Enter 确认、Esc/失焦取消。
Changes:
- sqlExecutionTarget.ts: add SqlExecutionCandidate, SqlExecutionOverride types
- sqlStatementRanges.ts: frontend SQL tokeniser (new, 848 lines)
- SqlExecutionTargetPicker.vue: accessible floating listbox (new, 109 lines)
- QueryEditor.vue: preview StateEffect/StateField; requestExecute() replaces
executeCurrentSql() to route through picker
- ContentArea.vue: expose requestQueryEditorExecute() to parent
- App.vue: toolbar + global shortcut → requestActiveEditorExecute()
- i18n: editor.executionPicker keys for all locales
- tests: 26 new unit tests for sqlStatementRanges (all 1121 tests pass)
uicky