Update App Manifest version to v1.26 across all templates

[Copilot]

Teams App Manifest schema v1.26 introduces new capabilities in description, composeExtensions, and copilotAgents. This updates all template files and the manifest package to target v1.26.

Schema changes (v1.25 → v1.26)

• description: New optional features array (minItems: 1, maxItems: 3, each item requires title + description)
• composeExtensions.authorization.authType: New oAuth2.0 enum value; requires oAuthConfiguration.oAuthConfigurationId when used
• copilotAgents: Relaxed from oneOf (requiring declarativeAgents or customEngineAgents) to unconstrained — neither is required

Changes

• packages/manifest/src/json-schemas/teams/v1.26/ — New schema file from microsoft/json-schemas@3e7df0c; two fixes applied to the upstream schema: corrected manifestVersion.const from "1.25" → "1.26" (upstream bug), and removed anyOf: [] from copilotAgents (empty anyOf is unrepresentable by quicktype)
• packages/manifest/src/generated-types/teams/TeamsManifestV1D26.ts — Auto-generated TypeScript types via npm run convert
• packages/manifest/src/generated-types/index.ts — Added v1.26 import/export, union type member, converter entry; updated TeamsManifestLatest to v1.26
• packages/mcp-server/src/fetcher.ts — Updated latestVersion for app_manifest to "v1.26"
• packages/mcp-server/tests/fetcher.test.ts — Updated expected schema URL to v1.26
• 123 template files — Updated $schema URL and manifestVersion field from 1.25 → 1.26

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Original prompt

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This section details on the original issue you should resolve

<issue_title>Update App Manifest Version to v1.26 in each template</issue_title>
<issue_description># App Manifest Schema Update v1.26

Latest Schema Commit: 3e7df0c

🎯 Impacted Properties We Support

The following properties used in our templates have been updated and require attention:

description ✅ NON-BREAKING

Change: Added a 'features' array property with required 'title' and 'description' fields, each with max length constraints and a min/max item count.

Impact: If the business logic expects or validates the 'description' property, it must now handle the 'features' array and enforce its constraints. Data submissions missing this array or violating constraints may fail validation, requiring UI and backend updates to support this structure.

composeExtensions ✅ NON-BREAKING

Change: 'authorization.authType' added new enum value 'oAuth2.0'. Introduced 'oAuthConfiguration' object, required when 'authType' is 'oAuth2.0'.

Impact: Logic handling 'composeExtensions' must now recognize and process the new 'oAuth2.0' auth type and validate the presence and structure of 'oAuthConfiguration' when applicable. Integration with OAuth flows and developer guidance/documentation will need updates to support this new authentication method.

copilotAgents ✅ NON-BREAKING

Change: Changed from 'oneOf' requiring either 'declarativeAgents' or 'customEngineAgents' to an empty 'anyOf' (no requirements).

Impact: Validation rules are relaxed; neither 'declarativeAgents' nor 'customEngineAgents' is required. This may allow more flexible agent definitions but could also result in incomplete or invalid agent configurations passing validation, potentially impacting downstream logic expecting at least one agent type.

📋 Action Required

Please update the following files in each template repository:

• manifest.json.tpl
• manifest.local.json.tpl (if applicable)
• manifest.dev.json.tpl (if applicable)

Note: Ensure all impacted properties listed above are properly updated according to the new schema requirements.

🔗 Related Work Item

Azure DevOps Work Item

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This issue was automatically generated by the Dependency Manager.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Update App Manifest Version to v1.26 in each template #15547

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