Dashboard 'registered vs installed' copy audit

[JSONbored]

Part of #5016. Low priority — cosmetic, no functional change. Best done last, after #1-#6 land so the "registered vs installed" split is fully accurate everywhere.

Context

/v1/app/overview (src/api/routes.ts:1230-1231), buildDigestItems (src/api/routes.ts:4568-4575), src/services/weekly-value-report.ts:134-135, and src/services/operator-dashboard.ts:141-142 already track installedRepos and registeredRepos as two separate, correctly-computed metrics side by side — this is not a bug. src/services/control-panel-roles.ts:75,111 (access-scope authorization) already uses isInstalled exclusively — the correct existing precedent this whole epic is generalizing.

Target

No functional change. Once gittensor is opt-in (see the plugin-toggle PR, landing separately from this epic), "0 registered" becomes the normal, expected state for most self-host operators. Audit dashboard/digest copy and confirm nothing reads as broken or alarming in that state (e.g. a stat tile that implies something is wrong when registered=0 but installed>0).

Deliverables

• Copy audit across the 4 files above (and any other surface displaying registeredRepos).
• Any wording fixes needed, no logic changes.

[linear-code]

JSO-3636

[JSONbored]

PR #5691 explicitly deferred this issue's copy audit ("sequenced into #5026... should land last"). The 4 target files it names are unchanged on current main. Leaving open.