feat: Android Chat, Video and Feeds skills

[gpunto]

Adding Android skills mirroring the structure of Swift ones

[martinmitrevski]

should we add one for xml components as well?

[andremion]

A few suggestions. Not blockers, just ideas to improve the Kotlin code the agent writes:

1. Add a short Kotlin-style section in sdk.md. The skills generate a lot of Kotlin, but never explain how to write it. Things to cover:

   • properties instead of getter functions (val foo: Foo get() = …)
   • named arguments for boolean flags
   • when instead of long if/else if chains
   • expression bodies for one-line functions
   • null-safety with ?. and ?: (use !! only when the value is guaranteed not to be null)
   • member references when readable (Channel::cid instead of { it.cid })

   About 15 lines, but without it, the agent often writes Java-style Kotlin in ViewModels and helpers.

2. Add a single line to RULES.md: do not use // region / // endregion comments. The agent tends to add them in long files.

3. Add a visibility rule to RULES.md: "Default to private or internal on new classes, functions, and properties. Use public only when something outside the file needs to access it." Without this, the agent makes everything public.

4. The "Blueprints are mandatory on every turn" rule already says to re-read the blueprint section. For follow-up edits, one more step would help: before changing an existing screen, search the project for callers and observers. Useful when the user asks for a small change to a file that the agent did not open in this session.

[gpunto]

A few suggestions. Not blockers, just ideas to improve the Kotlin code the agent writes:

Thanks for the suggestions! I'm going to check point 4 in particular. For the other ones, I think we should avoid giving broad style suggestions from a product-specific skill. They might conflict with the user's codebase style and their agents customization.