docs: use jni permission constant instead of magic string in llms.txt

feat: replace gomobile examples with real gomobile bind AAR build

Replace fake println-based examples with a real gomobile-bindable
package that produces an AAR via `gomobile bind`. The sensorbridge
package:

- Wraps sensor.Manager with int64 handle transport (gomobile bind
  cannot export unsafe.Pointer or uintptr)
- Builds to sensorbridge.aar with generated Java classes:
  Bridge(long managerHandle), accelerometerName(), handle(), etc.
- Includes Makefile for `make` to build the AAR
- Uses separate go.mod to avoid polluting the main module

Verified: `gomobile bind` produces 1.5MB AAR with correct Java API
(sensorbridge/Bridge.class, sensorbridge/Sensorbridge.class).

docs: merge examples into spoilers with complete code

Combine "Usage Examples" and "Other examples" into a single
"Examples" section. Wrap all examples in <details> spoilers.
Make main examples complete programs with package/imports/main.
Use current package constants (no magic values).

chore: remove deprecated NNAPI examples

NNAPI is deprecated since Android 15 (API 35). The replacement
(TFLite in Play Services) is a Java-only SDK, not part of the NDK.

fix: remove int32() cast for SetPreference in nnapi example

SetPreference now takes nnapi.Preference, not int32.

docs: add persistablebundle to README module table and update count t…

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