docs(m102): explain verified GitHub App routing

[indykish]

Docs updates for M102 agent identity proxy tail and connector ingress routing. Covers webhook security model and new webhook routing behavior for GitHub App installs.

Greptile Summary

This PR documents verified GitHub App setup and repository-bound fleet routing. The main changes are:

• Managed GitHub ingress and manual webhook paths are separated.
• Installation ownership, event filtering, fan-out, and replay handling are explained.
• Connector inspection commands and stable connector states are documented.
• Trigger configuration and related API error codes are updated.
• The changelog now includes the unmatched-subscription response.

Confidence Score: 5/5

This looks safe to merge.

• The changelog now documents the HTTP 404 and UZ-WH-022 response for signed deliveries with no matching fleet subscription.
• No blocking issue remains in the updated documentation.

Important Files Changed

Filename	Overview
changelog.mdx	Adds the GitHub App routing release note and documents the unmatched-subscription response.
api-reference/error-codes.mdx	Adds managed GitHub ingress errors and other generated registry entries.
cli/agentsfleet.mdx	Documents connector list and status commands.
fleets/authoring.mdx	Documents repository subscriptions for managed GitHub App triggers.
fleets/connectors.mdx	Explains verified installation ownership, setup, routing, and connector inspection.
fleets/webhooks.mdx	Separates managed ingress from manual webhooks and documents filtering and replay behavior.

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