Add supportsChannelFeatures tier1 to all app manifests

[singhk97]

Summary

• Adds "supportsChannelFeatures": "tier1" to the root of all 10 Teams app manifest.json.hbs template files
• Covers templates for Python (ai, echo, graph), TypeScript (ai, echo, graph, mcp, mcpclient, tab), and the ATK basic C# config

skip-test-verification

[singhk97]

@claude update the schema version to 1.25, add schema property "$schema": "{string}", if it doesn't exist. it should point to this https://developer.microsoft.com/json-schemas/teams/v1.25/MicrosoftTeams.schema.json. Ensure that there are no schema validation errors.