refactor!: always filter compiled browser runtime inputs

[longlho]

Why

Compiled browser inputs should contain runtime artifacts by default, without a separate switch that reintroduces transitive source and debug files into test cache keys.

Changes

• Remove runtime_only from the shared browser API and internal input rule. Runtime filtering is unconditional for compiled inputs and shell assets.
• Keep explicitly declared data, npm/runtime packages, and snapshot inputs unfiltered. Callers that need sources or maps at runtime must declare them as data.
• Remove obsolete enabled/disabled test variants while retaining coverage of source exclusion, directory map pruning, explicit data, runfile aliases, and original npm artifact paths.
• Document the explicit-data path for source-level debugging.

Existing callers using the default behavior are unchanged. Callers passing runtime_only must remove that argument; callers that previously disabled filtering must declare any required source/debug inputs explicitly.

[longlho]

Closing: retain the upstream runtime_only option. The consumer wrapper will stop exposing it and explicitly pass True instead.