fix(hig): name the status icons that carry a result as a symbol alone

[datlechin]

Follow-on to #2969. That one named controls; this one names state.

Eight status icons encode a result purely as a symbol plus a colour, with no text saying it. To VoiceOver they are silent, and to a colour-blind user two of them are the same glyph in two tints:

• App import preview (ConnectionImportPreviewList): ready / warning / unsupported. .ready deliberately carries no message, so the green check was the only carrier; .warnings and .unsupportedType are the same triangle in yellow and orange.
• AWS discovery progress: not started / done / failed. The adjacent text is the region id, a database count and a raw error message, none of which states the step's state.
• Plugin lists (BrowsePluginsView, PluginRejectedBannerModifier): restart-to-activate versus installed.
• AI settings: the checkmark marking the active provider. The text beside it says "API key set" or "Not configured", never which one is active.

Each now carries an .accessibilityLabel. Three of the strings already existed in the catalog (Warning, Failed, Done, Installed, Active); the rest are new keys and will read English until the next localization pass, which is how a new key behaves here.

What I did not touch, and why it matters

The audit counted 128 unlabelled literal-symbol images. 81 have adjacent text in the same container and are correctly decorative. I did not add .accessibilityHidden(true) to them, and checking them one by one is what stopped a regression:

• HistoryRowView.swift:70 and :73 look unlabelled for 60 lines in either direction. The label is applied at the call site (.accessibilityLabel(entry.wasSuccessful ? "Succeeded" : "Failed")). Hiding the icon would have deleted it.
• TableRowView.swift:108 is already inside a row that combines its children and appends "pending delete" to the composed label.

A blanket sweep would have hit both. The decorative class is real but it is polish, and the cost of getting one of them wrong is removing a control's only name, so it belongs in a change where each site is read.

Two more sites are genuinely meaning-bearing but cannot be fixed this way: ResultSetMenu:39 and AssistantPaneView:98 are the icon: of a menu item's Label, and VoiceOver reads the enclosing Button's label, so an .accessibilityLabel on the image is inert. Fixing those means composing the state into the Button's own label, which needs new format strings; that is a separate change rather than a silent no-op here.

Verification

• App scheme: BUILD SUCCEEDED, 0 errors.
• swiftlint lint --strict over the five changed files: 0 violations.