feat(phone): export privacy-safe diagnostics

[daniele21]

What changed

• adds a one-tap privacy-safe diagnostics snapshot to the connected phone app;
• exposes Copy all diagnostics and Export all diagnostics from the Diagnostics surface;
• exports app/build and physical-device identity, selected model identity, runtime snapshot, bounded generation runs, resource samples, health results, benchmark baselines/history and allowlisted structured logs;
• includes generation breakdown needed for performance investigations: queue, model load, prompt planning, context creation, TTFT, prefill, decode, total latency, token counts, throughput, context, preset/sampling, thinking mode and stop reason;
• preserves the existing privacy boundary: no prompt, generated output, URI, filesystem path or arbitrary backend message is exported;
• clarifies in-product Resources and Benchmarks semantics: resources are explicitly captured snapshots; benchmark baselines are derived from matching completed inference runs and require five matching samples before capture;
• adds deterministic unit coverage for the exported run projection using a severe-latency fixture.

Why

Physical-device testing exposed a large inference slowdown that cannot be diagnosed from the current condensed Diagnostics cards alone. A bounded shareable snapshot lets device observations be reviewed without ADB or access to private app storage and without weakening the telemetry privacy model.

Validation

Keep draft until exact-head phone unit/lint/compile checks and repository Validate are green against current dev.