Remove every as any from the test suite and enforce it

ESLint turned `no-explicit-any` off for test files, and 219 casts had
accumulated across 12 of them. Two shapes, very different risks: most
were `(useWorkspace as any).mockReturnValue(...)`, mere laziness that
`vi.mocked()` does properly; the rest cast partial fixtures onto API
types, which erases the contract exactly where a test should enforce it.

That second kind matters here specifically. This project's recurring bug
is a field silently dropped between backend and frontend -- the
hand-written mapping in models/plan.py has done it twice, and apiFetch
mishandling structured errors was the same shape. A test that casts an
incomplete fixture to `any` keeps passing through precisely that change.

A typed fixture layer already existed at tests/fixtures/mockData.ts and
was imported by exactly zero tests: the right tool was there and
invisible, so everyone reached for a cast. It is now a set of
`make*(overrides: Partial<T>) => T` factories returning complete, valid
objects, split by domain with a barrel. When a type gains a field, one
factory fails to compile instead of thirty tests silently passing.

With the count at zero the ESLint exemption is deleted, so this cannot
regrow. Removing it immediately caught two `}: any` prop stubs that a
grep for "as any" had missed; those mocks now use the real components'
exported prop types.

`as unknown as T` survives in five places, each a test deliberately
feeding invalid input (an undefined breakdown, missing tierData, a bogus
leave type). CLAUDE.md now documents that as the only accepted escape,
and points at the factories.

interface PollResponse in useScraperFetch.ts is exported so its shape can
be derived rather than duplicated -- pollScraperSession declares
Promise<unknown>, so there was no other honest way to type it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RXMhc9nT6sNz1SL4j8dznL

CLAUDE.md

@@ -173,7 +173,7 @@ that were in fact failing.
 
 ## ANTI-PATTERNS (CRITICAL GUARDRAILS)
 
-* **Type Safety (TS):** No type suppression — no `as any`, `@ts-ignore`, or `@ts-expect-error`. `no-explicit-any` is an ESLint error and CI fails on warnings.
+* **Type Safety (TS):** No type suppression — no `as any`, `@ts-ignore`, or `@ts-expect-error`. `no-explicit-any` is an ESLint error and CI fails on warnings. **This applies to test files too** — there is no exemption. Build mock data with the typed factories in `frontend/tests/fixtures/` (`makeWorkspaceOverview`, `makePlanProposal`, `make*Result`, …), which return complete, correctly-typed objects you override with a `Partial<T>`, and mock functions with `vi.mocked(fn)` rather than casting. A cast in a test defeats the type check exactly where it guards the frontend/backend contract — which is this project's most common bug. The one accepted escape is `as unknown as T` in a test that *deliberately* exercises invalid input (a missing field, a bogus enum value); keep it to that expression and comment why.
 * **Type Safety (Python):** No bare `# type: ignore` to silence the type checker; fix the underlying type or model instead. Prefer precise Pydantic models over `dict[str, Any]` at API boundaries.
 * **Error Handling:** No empty `catch`/`except` blocks. Explicit handling/logging is required. Backend errors should flow through `app/utils/errors.py`; frontend errors through `src/services/errors.ts`.
 * **Testing Integrity:** NEVER delete or comment out failing tests to make a suite "pass". Fix the code, or update the test properly with a clear reason.