[User Story] As a developer, I want to be able to make issue references inside project channels

**Given...**
Given I accept the bot to overwrite my messages with issue references (by a command like `c!github iss-ref true`)

**When...**
When I send a message with a issue reference in a project channel.

> We shall fix #69 and merge #70 quickly

**Then...**
Then the bot copy my message, deletes it and resend referencing the issue. (using a hyperlink)

> [{user}]: We shall fix [#69]\(https://github.com/Code2Gether-Discord/{channel}/issue/69) and merge [#70]\(https://github.com/Code2Gether-Discord/{channel}/pull/70)

Start by locating the bot command handling for `c!github iss-ref true` and the message-processing entry point for project channels. Trace how messages are received, deleted, and resent, then verify behavior with references to both an issue and a pull request. Done means opted-in users' messages are replaced with hyperlinks while other messages remain unchanged.

索引モデルが issue の本文から書いたものです。