feat(profile): migrate profile and report activity page to Next.js

[vbeni30]

What does this PR do?

Migrates the legacy Razor /profile route to a native Next.js page, fully utilizing the App Router.

• Built the new Next.js route at frontend/app/profile/page.tsx using server-side data fetching for the initial load.
• Removed the legacy /profile rewrite rule from next.config.ts.
• Integrated ProfileFullView as the main layout, wiring up the filter sidebar, date range dropdown, chart, and data tables.
• Fixed a layout bug in the empty states where stats and charts would completely disappear when a user had no activity data. It now correctly falls back to placeholders (-) and an empty UI state, matching the old Razor layout perfectly.
• Added comprehensive unit tests in profile-full-view.test.tsx to handle loading, error, and empty states gracefully.

Testing

• Tests are all passing locally.
• You can pull down this branch, run npm run frontend:dev, and visit /profile to check out the migrated Next.js UI.

Sceenshot

[Seme30]

Review findings

I reviewed this against issue #769. The current implementation has blockers:

1. P1 — /profile resolves to the wrong profile: frontend/app/profile/page.tsx:48-54 redirects the bare /profile route to the signed-in user with type=user. The legacy Report Activity route uses type=report and id=-1; /users is the separate personal-profile route. This changes the route semantics and hides the Report Runs, Stars, and Subscriptions sections.

2. P1 — The required filter sidebar is empty: frontend/components/profile/profile-filter-sidebar.tsx:20-32 now renders only the Filter Profile heading. The PR deletes its controls and does not implement the Razor-equivalent server, database, master-file, visibility, certification, availability, or report-type filters. The date-range selector elsewhere does not satisfy the profile filter acceptance criterion.

3. P2 — Real API failures do not reach the tested error state: frontend/app/profile/actions.ts:60-79 returns a populated data object with error: null for forbidden, not-found, server-error, and service-unavailable responses, converting failed sections to null or empty arrays. Consequently, the error branch in frontend/app/profile/page.tsx:70 is normally unreachable for these failures. The new component test mocks { data: null, error: "service_unavailable" }, but the action does not produce that result.

The CI checks pass, but these acceptance-level behaviors are not covered. Please address them before merging.

[Seme30]

The latest commit resolves the API error-propagation issue, but two blockers from the previous review remain:

1. P1 — Bare /profile still resolves to the wrong profile. frontend/app/profile/page.tsx still redirects to the signed-in user with type=user. The legacy Report Activity route requires type=report and id=-1; /users is the personal-profile route. This continues to hide Report Runs, Stars, and Subscriptions for the bare route.

2. P1 — Required profile filters are still missing. frontend/components/profile/profile-filter-sidebar.tsx remains effectively empty and does not provide the Razor-equivalent server, database, master-file, visibility, certification, availability, and report-type filters.

Please address these before merging.