v0.2.6 — filter-based AI connector discovery

Refactor — ConnectionMethodRegistry::get_ai_connectors() now sources DTOs from a WordPress filter

The Discovery API's ai_connector category is now populated via the new filter acrossai_mcp_manager_discovery_ai_connectors instead of a direct call to the paid companion plugin's ConnectorProfileRegistry class.

• Companion (acrossai-pro 0.8.0+, already released) hooks the filter and returns the same DTO shape from its own registry — Discovery's ai_connector category behaves identically for end users.
• Removes the hardcoded FQN string \AcrossAI_AI_Connectors\Includes\Connectors\ConnectorProfileRegistry from the free plugin, so future companion renames/restructures don't silently break Discovery.
• Fail-safe unchanged: with no companion active, the filter returns an empty array and the ai_connector category is omitted from Discovery — no fatal, no warning.

Internal

• ACROSSAI_MCP_MANAGER_VERSION constant + Stable tag bumped to 0.2.6 matching the plugin header.

PR: #73
Full diff: v0.2.5…v0.2.6