Render apply_patch tool calls as structured diffs

[zcmx]

Problem

apply_patch tool calls currently fall back to the generic tool renderer, which makes multi-file patches difficult to scan in chat.

Changes

• Add a dedicated expanded widget for apply_patch calls.
• Parse add, update, move, and delete file sections from patch text.
• Show per-file operation labels and addition/deletion counts.
• Render added, removed, and context lines with distinct colors.
• Provide a concise compact description with affected-file and line counts.
• Fall back to the generic tool view when the patch payload cannot be parsed safely.

This PR contains only the apply-patch presentation change. Todo/reasoning UI, model persistence, SSE recovery, and hardened-build changes are not included.

Verification

• ApplyPatchToolWidgetTest
• :app:detekt
• git diff --check

Local Android unit-test execution is blocked on this machine by the existing Java/Kotlin target mismatch in main (compileDebugJavaWithJavac targets 17 while compileDebugKotlin targets 21). The same widget tests passed in the downstream integrated branch where the toolchain is aligned.