fix(context): refresh workspace state after tool-driven file changes

[ashishsinghbora]

Problem

"WorkspaceContext" and the generated prompt prefix are constructed once when "MiniAgent" starts. However, tools such as "write_file", "patch_file", and "run_shell" can mutate the workspace during the same session.

As a result, subsequent model turns can receive stale information about:

• "git status"
• current branch state
• recent commits
• project documentation
• repository-level instructions

For example, the initial workspace may be clean, but after "write_file" creates a file, the prompt can still report the original clean status.

Expected behavior

After workspace-mutating operations, the agent should either:

1. refresh the affected workspace context, or
2. explicitly separate immutable context from dynamically refreshed state.

The refresh should avoid rebuilding unnecessary static prompt content on every turn.

Acceptance criteria

• "git status" reflects changes made during the current session.
• Changes made through "write_file", "patch_file", and shell commands are visible to later model turns.
• Project documentation changes are reflected when appropriate.
• Existing prompt/cache behavior is preserved as much as possible.
• Add regression tests covering a workspace mutation followed by another model turn.