Use dynamic Obsidian vault config path

Obsidian's configuration directory isn't necessarily .obsidian, it can be configured by the user. You can access the configured value from Vault#configDir.

https://github.com/jacksteamdev/obsidian-mcp-tools/blob/72beac26b79ab99205dc68cc60e4037c6e79b182/packages/obsidian-plugin/scripts/link.ts#L16

From https://github.com/obsidianmd/obsidian-releases/pull/5060#issuecomment-2570035595