feat: Add "Copy as SQL List" context menu commands for SQL editors

[bobcozzi]

Summary

Adds two new right-click context menu commands to SQL editors, available whenever text is selected. This addresses a feature request from the IBM i OSS community where users wanted a quick way to convert a plain newline-separated list of values (e.g. product codes, order numbers) into a SQL-friendly quoted, comma-separated list for use in IN clauses and similar constructs — without leaving VS Code to use another tool like dBeaver.

Community request: https://chat.ibmioss.org/#narrow/channel/8-vscode/topic/Seb's.20Extension.20Example.20Part.20deux/with/4188

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New Commands

Db2 for i: Copy as SQL List

Instantly copies the selected newline-separated values to the clipboard using the user's current settings. No prompt — fast path for users who code quickly and want a single keystroke-style experience.

Db2 for i: Copy as SQL List (Prompt Format)

Shows a QuickPick menu with format options before copying. When the selection contains numeric values, additional unquoted variants are offered:

Option	Example output
Copy as list	'S10_1678', 'S10_1949', 'S10_2016'
Copy as list (numbers unquoted)	'ABC', 123, 'DEF'
Copy wrapped in parentheses	('S10_1678', 'S10_1949', 'S10_2016')
Copy wrapped in parentheses (numbers unquoted)	('ABC', 123, 'DEF')

Both commands only appear in the context menu and command palette when a SQL file has an active text selection (editorLangId == sql && editorHasSelection).

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New Settings

Setting	Type	Default	Description
vscode-db2i.delimitedList.quoteNumbers	boolean	true	Whether the instant-copy command quotes numeric values
vscode-db2i.delimitedList.wrapInParentheses	boolean	false	Whether the instant-copy command wraps the list in parentheses

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Implementation Notes

• SQL-safe quoting: Internal single quotes are escaped as '' (e.g. O'Brien → 'O''Brien')
• Blank line filtering: Empty/whitespace-only lines in the selection are silently ignored
• Large selection guard: A modal confirmation is shown if more than 256 values are selected
• Clipboard error handling: clipboard.writeText() failures surface a descriptive error message rather than failing silently
• New file: src/language/clipboard.ts — follows the same initialise(context) pattern as src/language/json.ts