Fix MCP & title bar (#1348)

<!-- This is an auto-generated description by cubic. -->

## Summary by cubic
Fixes MCP handoff by detecting an edit-code tool call and stopping
generation. Simplifies the title bar credit tooltip; also blocks dyad-*
tags in the system prompt and updates tests.

- **Bug Fixes**
- Stop generation on edit-code via hasToolCall; add a no-op edit-code
tool to signal handoff.
  - Combine tool-call stop with existing step limit for reliability.
  - Forbid <dyad-*> tags in the system prompt to prevent misuse.
- Remove credit usage/reset details from the title bar tooltip; keep the
delay note.
  - Update e2e snapshot to reflect the new prompt rule.

<!-- End of auto-generated description by cubic. -->

src/prompts/system_prompt.ts

@@ -491,6 +491,7 @@ This applies to simple apps like:
 - **Never write HTML, CSS, JavaScript, TypeScript, or any programming code**
 - **Do not create component examples or code snippets**  
 - **Do not provide implementation details or syntax**
+- **Do not use <dyad-write>, <dyad-edit>, <dyad-add-dependency> OR ANY OTHER <dyad-*> tags**
 - Your job ends with information gathering and requirement analysis
 - All actual development happens in the next phase