Document Launchplane agent-context boundary

[cbusillo]

Problem

Launchplane needs durable docs before public skills consume agent-facing context so future work preserves the boundary between GitHub planning truth, Launchplane runtime evidence, and optional skill helpers.

Scope

• Document agent authz subjects and safety levels.
• Document redaction, freshness, provenance, and no-plaintext-secret rules.
• Document read models and final aggregation endpoint once stable.
• Document write-intent flows and approval/dry-run expectations.
• Document how codex-skills should consume Launchplane context without hardcoding private hosts or copying issue bodies.

Acceptance Criteria

• Service boundary, work graph, operator experience, records/secrets, and any new agent-context docs are consistent.
• Docs state GitHub remains planning/code workflow truth.
• Docs state Launchplane compiles product/runtime/evidence context and scoped intents.
• Docs are updated in the same PRs that add or change agent-facing behavior.

Relationships

• Subissue of Make Launchplane a read-only agent context provider #379.
• Blocks final public skill integration docs in Consume Launchplane agent context from public-safe skills codex-skills#3.