[docs] decision: emulation overrides are exposed through named convenience methods

[AutomatedTester]

💥 What does this PR do?

Proposes a design decision record: emulation overrides are exposed through named convenience methods.

BiDi defines eleven emulation.set*Override commands (geolocation, locale, timezone, user agent, network conditions, forced colors, touch, …). The bindings already generate a method per command from CDDL, so all of it is reachable — but only in raw wire shape, which makes a simple "set location to Paris" more ceremony than it should be and leaves the emulation surface undiscoverable. This record proposes thin, consistent, named convenience methods (set_geolocation, set_locale, set_timezone, set_user_agent, set_network_conditions, set_forced_colors, set_touch) over the generated commands, preserving BiDi's dynamic mid-session application and keeping the raw methods as an escape hatch.

🔧 Implementation Notes

• Follows the docs/decisions/ process from [docs] add design decision record process and template #17665 — depends on [docs] add design decision record process and template #17665 landing (adds only docs/decisions/0005-*.md).
• These are not protocol gaps — the commands exist and are implemented; the decision is purely about a friendly, cross-binding-consistent wrapper layer. Names/arg-names are part of what's being decided so the five bindings don't drift.
• No wire-protocol change; thin and additive.

🤖 AI assistance

• AI assisted (complete below)
  • Tool(s): Claude Code
  • What was generated: Initial draft of the decision record, derived from a CDDL-validated comparison of the Python BiDi surface against Playwright; revised through discussion and review
  • I reviewed all AI output and can explain the change

💡 Additional Considerations

One of a set of BiDi ergonomics decision records proposed together. The convenience set is deliberately scoped to high-use overrides; the remaining commands stay raw until there's demand. Cross-binding convergence is tracked in the binding-status table.

🔄 Types of changes

• Documentation (design decision record)