feat(ai): Add App Functions for system AI integration

[jamesarich]

Motivation

Enable system AI assistants (Gemini, etc.) to interact with Meshtastic mesh networks through the Android AppFunctions framework. This gives AI agents read access to mesh status, nodes, channels, messages, and metrics -- plus the ability to send messages -- without opening the app UI.

Approach

Implements 9 App Functions in a layered KMP architecture:

• Core layer (core/data/ai/): Platform-agnostic AiFunctionProvider interface and implementation with rate limiting, fuzzy name resolution, and proper error handling
• Android layer (androidApp/src/google/): @AppFunction declarations with @AppFunctionSerializable response models, wired via Koin DI
• Google flavor only: Functions are only available in the Google Play build (requires Play Services for the AppFunctions runtime)

Functions implemented

Function	Type	Description
sendMessage	Write	Send a text message to a node or channel
getMeshStatus	Read	Connection state + node counts
getNodeList	Read	All nodes with name, signal, battery, coordinates
getChannelInfo	Read	Channel name, role, and PSK status
getDeviceStatus	Read	Local radio firmware, battery, region
getNodeDetails	Read	Detailed info for a specific node
getMeshMetrics	Read	Network health metrics (online ratio, signal stats)
getRecentMessages	Read	Recent message history with contact resolution
getUnreadSummary	Read	Unread message counts per contact

Notable design decisions

• Rate limiting: 10 requests/minute per function to prevent AI loops from overwhelming the radio
• Fuzzy name resolution: Contacts can be referenced by partial name match (e.g., "James" resolves to the correct node)
• Graceful disconnection handling: Functions that can answer from local DB (messages, unread) work even when disconnected; others return clear error messages
• KDoc compliance: All @AppFunctionSerializable properties use inline KDoc (not class-level @property tags) per KSP extraction requirements
• app_metadata.xml: Provides LLM-facing operational patterns and constraints for the AI runtime

Testing

• Unit tests for core provider logic (edge cases, error paths)
• End-to-end verified on android-36.1 emulator via adb shell cmd app_function execute-app-function -- all 9 functions respond correctly
• Note: android-36.1 system image is required for ADB AppFunction shell testing (base API 36 and ext19 lack the shell command)

[github-actions]

📄 Docs staleness check — advisory

This PR modifies user-facing UI source files but does not update any page under docs/en/user/ or docs/en/developer/.

⚠️ Doc changes propagate to 3 consumers: in-app docs browser, Jekyll site (GitHub Pages), and meshtastic.org (Docusaurus sync). Updating a page in docs/en/ automatically flows to all three.

Changed source files:

core/ui/src/commonMain/kotlin/org/meshtastic/core/ui/component/BuildNodeDescription.kt
core/ui/src/commonMain/kotlin/org/meshtastic/core/ui/component/LastHeardInfo.kt
core/ui/src/commonMain/kotlin/org/meshtastic/core/ui/component/MaterialBatteryInfo.kt
core/ui/src/commonMain/kotlin/org/meshtastic/core/ui/component/NodeCardGlow.kt
core/ui/src/commonMain/kotlin/org/meshtastic/core/ui/component/NodeItemCompact.kt
core/ui/src/commonMain/kotlin/org/meshtastic/core/ui/component/TelemetryInfo.kt
core/ui/src/commonMain/kotlin/org/meshtastic/core/ui/component/TransportIcon.kt
feature/docs/src/commonMain/kotlin/org/meshtastic/feature/docs/ui/ChirpyAssistantSheet.kt
feature/docs/src/commonMain/kotlin/org/meshtastic/feature/docs/ui/ChirpyFab.kt
feature/docs/src/commonMain/kotlin/org/meshtastic/feature/docs/ui/DocsBrowserScreen.kt
feature/docs/src/commonMain/kotlin/org/meshtastic/feature/docs/ui/DocsPageRouteScreen.kt
feature/messaging/src/commonMain/kotlin/org/meshtastic/feature/messaging/component/MessageItem.kt
feature/node/src/commonMain/kotlin/org/meshtastic/feature/node/component/DeviceDetailsSection.kt
feature/node/src/commonMain/kotlin/org/meshtastic/feature/node/component/NodeDetailsSection.kt
feature/node/src/commonMain/kotlin/org/meshtastic/feature/node/component/NodeItem.kt
feature/node/src/commonMain/kotlin/org/meshtastic/feature/node/component/NodeListHelp.kt
feature/node/src/commonMain/kotlin/org/meshtastic/feature/node/component/NodeStatusIcons.kt
feature/settings/src/commonMain/kotlin/org/meshtastic/feature/settings/component/NodeLayoutSettings.kt

What to check:

Changed area	Likely doc page
feature/messaging/	docs/en/user/messages-and-channels.md
feature/node/	docs/en/user/nodes.md or docs/en/user/node-metrics.md
feature/map/	docs/en/user/map-and-waypoints.md
feature/connections/	docs/en/user/connections.md
feature/settings/	docs/en/user/settings-radio-user.md or docs/en/user/settings-module-admin.md
feature/firmware/	docs/en/user/firmware.md
feature/intro/	docs/en/user/onboarding.md
feature/discovery/	docs/en/user/discovery.md
feature/docs/	Internal docs infrastructure
core/ui/	docs/en/developer/codebase.md or component-specific user pages

New page checklist (if adding a new doc page):

1. Create the .md file in docs/en/user/ or docs/en/developer/ with last_updated frontmatter
2. Register in DocBundleLoader.kt with string resources (in-app browser)
3. Jekyll and Docusaurus sync pick up new pages automatically — no config change needed

If this PR does not require a doc update (e.g., internal refactor, bug fix, test change), add the skip-docs-check label to dismiss this check.

Cross-platform note: This check is advisory while doc coverage matures. Both Android and Apple repos use the same skip-docs-check label and advisory severity. See meshtastic/design standards for shared conventions.