Make `silencedConsole` require explicit method selection

[williamthorsen]

Problem

silencedConsole() silences all five console methods (log, error, warn, info, debug) unconditionally. This masks unexpected console output that might reveal bugs, and developers default to silencing everything because it's the path of least resistance.

Context

The utility lives in packages/factory/src/test-utils.ts and is used across ~20 test call sites. Most callers only need to silence error (they're testing error paths). Three callers assert on specific methods (silent.error, silent.warn).

Solution

Make the methods parameter required so callers must specify which console methods to silence. The return type narrows to only include the requested methods, giving a compile-time error if a caller asserts on a method they didn't silence.

silencedConsole(['error'])        // → { error: MockInstance } & Disposable
silencedConsole(['error', 'warn']) // → { error: MockInstance; warn: MockInstance } & Disposable

All existing call sites move to silencedConsole(['error']). The three assertion sites keep their current method lists.

Acceptance criteria

• silencedConsole requires an array of method names (no default "all" behavior)
• Return type is narrowed to only the requested methods
• All existing call sites updated
• All tests pass

[williamthorsen]

Insight: vi.spyOn conditional-type resolution for union-typed method names

vi.spyOn(console, method).mockImplementation(() => {}) fails to typecheck when method is a union type (e.g., 'error' | 'warn') because TypeScript can't resolve spyOn's conditional return type across the union branches for the chained .mockImplementation() call.

The common workaround is an exhaustive switch that narrows the union to each literal. But this is unnecessary — splitting the chain onto separate statements is sufficient:

const spy = vi.spyOn(console, method);
spy.mockImplementation(() => {});
return spy;

TypeScript resolves spyOn's overload to a union of spy types on the first statement, and mockImplementation(() => {}) is assignable to all branches of that union on the second. No type assertions, no switch, no eslint-disable.