Rename Copy site to Duplicate site

[nightnei]

How AI was used in this PR

Didn't use

Proposed Changes

NIT Every time I see "Copy site" - I feel confused. Maybe it's personal, but I used to see word "Duplicate" in such cases. And when I see "Copy", I expect to paste it somewhere.
I propose to rename to "Duplicate site".
macOS example:

Testing Instructions

Visual review should suffice

[wpmobilebot]

📊 Performance Test Results

Comparing eaba0aa vs trunk

app-size

Metric	trunk	eaba0aa	Diff	Change
App Size (Mac)	1358.05 MB	1358.04 MB	0.01 MB	⚪ 0.0%

site-editor

Metric	trunk	eaba0aa	Diff	Change
load	1655 ms	1618 ms	37 ms	⚪ 0.0%

site-startup

Metric	trunk	eaba0aa	Diff	Change
siteCreation	9039 ms	9045 ms	+6 ms	⚪ 0.0%
siteStartup	4426 ms	4414 ms	12 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)

[epeicher]

Thanks @nightnei! I agree this is slightly clearer. I have reviewed, and this LGTM! But happy to hear other thoughts

[fredrikekelund]

I agree "Duplicate" is clearer. With "Copy", I don't know if there will be an intermediate step or not. With "Duplicate", I understand that there will be a new copy of the site available straight away