feat: add usage onboarding survey overlay (#388)

* feat: add usage-survey feedback types and gating function

Claude-Session: https://claude.ai/code/session_01KAC9Lbx8AmebAnj9WQZXHp

* feat: add onboarding usage-survey i18n strings to all locales

Relabels three ambiguous feedback.usageTypes values (personal/team_internal/
business_workflow) and adds a new onboarding namespace (4 keys) across the
reference locale and all 20 translations, so the tree compiles at every
commit instead of only after both locale groups land.

Claude-Session: https://claude.ai/code/session_01KAC9Lbx8AmebAnj9WQZXHp

* feat: add UsageSurveyOverlay component

* feat: mount UsageSurveyOverlay inside AuthGuard

Claude-Session: https://claude.ai/code/session_01KAC9Lbx8AmebAnj9WQZXHp

* fix: use text-start instead of text-left for RTL support in UsageSurveyOverlay

* refactor: drop redundant usage-type field from the admin feedback dialog

Claude-Session: https://claude.ai/code/session_01KAC9Lbx8AmebAnj9WQZXHp

* feat: accept onboarding source and survey id in the feedback route

Claude-Session: https://claude.ai/code/session_01KAC9Lbx8AmebAnj9WQZXHp

* test: cover the onboarding source in the feedback route integration test

Claude-Session: https://claude.ai/code/session_01KAC9Lbx8AmebAnj9WQZXHp

* chore: remove orphaned usageTypeLabel i18n key

* refactor: derive feedback source/survey_id enums from a single source of truth

* perf: skip the settings fetch in UsageSurveyOverlay for non-admin users

tests/unit/web/feedback-dialog.test.tsx

@@ -26,9 +26,6 @@ describe("FeedbackDialog", () => {
     fireEvent.change(screen.getByLabelText("Install method"), {
       target: { value: "docker_compose" },
     });
-    fireEvent.change(screen.getByLabelText("Use case"), {
-      target: { value: "team_internal" },
-    });
     fireEvent.change(screen.getByLabelText("Hardest setup area"), {
       target: { value: "environment_variables" },
     });
@@ -52,7 +49,6 @@ describe("FeedbackDialog", () => {
         contactName: undefined,
         company: undefined,
         installMethod: "docker_compose",
-        usageType: "team_internal",
         frictionArea: "environment_variables",
         importantAreas: ["pdf_docs", "batch_workflows"],
       });