[NO QA] Docs updates for E/A#86938 Add undelete and deleted expense filter docs

[MelvinBot]

Summary

• Added documentation for finding and undeleting deleted expenses in How to Delete Expenses
• Added "Deleted" to the expense status filter examples in Getting Started with the Reports Page
• Added Undelete action to the secondary actions table in Expense and Report Actions
• Updated keywords and internal scope metadata to cover the new undelete workflow

These changes reflect the new deleted transactions search and undelete feature introduced in #86938.

Test plan

• Verify the help site renders correctly with the new content
• Confirm the Undelete steps match the actual UI flow
• Confirm the Deleted status filter is listed accurately

[MelvinBot]

Fixed the failing spellcheck: added undeleting to the cspell dictionary (it was flagged in How-to-Delete-Expenses.md line 5).

[MelvinBot]

The perf-tests failure is unrelated to this PR.

Failure: SidebarLinks render count exceeded the allowed deviation of 0 (current difference: 1).

Why it's unrelated: This PR only modifies documentation markdown files and cspell.json — no JS/TS code changes that could affect render counts. This is a pre-existing flaky perf test.

The only other failing check is checklist, which is the PR Author Checklist and not a code issue.