fix(husky): stage server files from worktree root in pre-commit hook (#41835)

## Summary
- Pre-commit hook stages server files at the wrong path when committing
from a linked git worktree, creating an orphan tree at the worktree root
in addition to the correct entry.
- Root cause: git invokes hooks with `GIT_DIR` set but `GIT_WORK_TREE`
unset. After `pushd app/server`, `git add` falls back to treating cwd as
the worktree root, so `xargs git add appsmith-interfaces/...` (with the
`app/server/` prefix stripped) stages files at the wrong location. Only
affects worktrees, not the main checkout.
- Fix: run `mvn spotless:apply` in a subshell (so the script's cwd stays
at worktree root), and stage with full `app/server/...` paths via the
unchanged path list. Same behavior in the main checkout; correct
behavior in worktrees.

## Reproduction
In a linked worktree with a staged change under `app/server/`, the hook
stages the file twice — once correctly and once at the worktree root
without the `app/server/` prefix. Verified by simulating the hook env
(`GIT_DIR` set, cwd at `app/server/`) and running the old vs new `git
add` invocation; old path produces the duplicate orphan entry, new path
produces only the correct entry.

## Test plan
- [ ] Commit a server file change from a linked git worktree (`git
worktree add ...`); confirm `git status` after commit shows no orphan
entries at the worktree root.
- [ ] Commit a server file change from the main checkout; confirm
spotless still runs and re-staging works as before.
- [ ] Commit a client-only change; confirm `lint-staged` still runs.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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## Summary by CodeRabbit

* **Chores**
* Updated internal code formatting automation to improve developer
workflow efficiency.

---

**Note:** This release contains no user-facing changes. The update
addresses internal development tooling.

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Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>