diff: the focus hook answers to either name the engine stamps on its elements - #96953

The mod's ui.focus hook matched the elements it drew through its own name, one constant ({ plugin: Names.PLUGIN_NAME }, 'diff'). The engine stamps an element with the name the plugin is registered under, and a build that carries this mod registers it as cc-plugin-diff. With a single name in the matcher the hook would stop seeing its own elements there, and silently: the inline file list would no longer follow the focus ring, and nothing would say why.

A matcher takes an array as any-of, so the constant is now the two names, PLUGIN_NAMES = ['diff', 'cc-plugin-diff']. Loaded from this folder (--plugin-dir, claude plugin test) the mod is diff, as its manifest says, and nothing changes. The addresses the tests press ($.ui.press({ plugin: 'diff', ... })) are resolved against that manifest name, so they stay as they are.

Checked:

• mods/diff/tests/views.test.ts: a new case, "the walk follows under the name a build registers", raises the same walk with the focus stamped cc-plugin-diff and expects the same recentring. With the matcher put back to the single name, that case is the one that fails (157 pass, 1 fail).
• Against a current build, at this branch's head: the mods' typecheck passes and claude plugin test mods/diff passes 158 of 158.