fix(git): preserve full diff hunk headers

[em0t]

Summary

• preserve the full unified diff hunk header in rtk git diff compact output instead of reconstructing it without trailing context
• keep function / symbol context that appears after the second @@ marker
• add regression coverage for hunk headers such as @@ -10,3 +10,4 @@ fn important_context() {

Minimal Case

Raw

@@ -10,3 +10,4 @@ fn important_context() {

Previous RTK

@@ -10,3 +10,4 @@

This PR

@@ -10,3 +10,4 @@ fn important_context() {

Testing

• cargo fmt --all
• cargo clippy --all-targets
• cargo test --all

Notes

• cargo clippy --all-targets still reports pre-existing warnings outside this change set

[CLAassistant]

All committers have signed the CLA.

[em0t]

Could a maintainer please approve and run workflows so CI can start for review?

[aeppling]

Hello, valid & merged

Thanks for contributing