docs(framework): hooks documentation, tool-internal vs pre-commit #303

Problem

The framework ships bundled hooks, but authors lack one documented, host-aware contract for adding a hook.

Scope

• Extend the existing bundled-hooks section in docs/ARCHITECTURE.md with the minimal hook contract, supported lifecycle mapping, and the boundary with Git hooks.
• Link that section from docs/CREATE_PLUGIN.md.
• Correct docs/GLOSSARY.md: Git pre-commit is not an agent lifecycle event.

Acceptance criteria

• An author can add a basic hook from ARCHITECTURE.md without reading an existing implementation.
• Supported lifecycle events and per-host coverage are explicit.
• The agent-hook versus Git-pre-commit boundary is explicit.
• CREATE_PLUGIN.md links to the authoritative section.
• The glossary no longer classifies pre-commit as an agent lifecycle event.

Prior art in this repo

• ARCHITECTURE.md already inventories Context and Telemetry hooks, but does not define an authoring contract.
• Context and Telemetry have declarative hooks; OpenCode uses a JavaScript plugin bridge.
• Claude Code Hooks documents more events than AIDD currently normalizes.

Out of scope

• Changing or adding a bundled hook.
• Installing Git pre-commit hooks or adding CI enforcement.
• Claiming lifecycle parity that a host has not demonstrated.