fix(web/mobile): render project images in nested markdown file previews and harden markdown images - #7857

💭 This PR only touches markdown image rendering in React components and a pure helper function, with no Effect service code involved, so the review looks clean. I need to format the response as JSON per the schema rather than a plain text confirmation, since that's the mandatory output format.

1. git_tools — Effect|Layer|Context.Service|ManagedRuntime|runPromise — rejected: repo.url: required parameter is missing or empty;repo: required parameter is missing or empty

2. git_tools — from "effect|ManagedRuntime|runPromise|Layer.succeed — rejected: repo.url: required parameter is missing or empty;repo: required parameter is missing or empty

3. git_tools — ManagedRuntime|runPromise|Layer.succeed|Context.Service

4. git_tools — effect

💭 Checking the changed files, they're just UI/markdown code with no Effect service definitions or imports, so no Effect conventions apply here. All clear.