[codex] Add local action execution substrate

[snbafana]

Summary

• Adds a local action substrate with action definitions, approval/execution state, effect recording, and skill-loaded CJS executors.
• Reworks contact memory and contact merge mutations to go through actions, with daemon and CLI support for proposing, approving, executing, and running approved work.
• Bundles Cued action definitions/executors, updates skill installation/status reporting, adds action smoke scripts, and includes action files in release artifact validation.
• Switches adapter invocation cursor/proof state toward generic env names and removes more legacy naming/schema paths.

Review notes

• The direction makes sense for local agent-owned durable actions: proposed work is auditable, approval-gated, executable by the daemon, and replayable through effects.
• Main concern: the migration system is replaced by CURRENT_SCHEMA_SQL, which creates missing tables but does not alter partially upgraded existing DBs. This needs explicit upgrade coverage before shipping broadly.
• Main concern: existing contact_merge_decisions rows are not read or migrated into action_effects, so prior manual merge aliases may disappear on rebuild.
• Main concern: an older local ~/.cued/skills/cued install can shadow the bundled skills/cued actions and leave the registry with zero built-in action definitions.

Validation

• pnpm check:biome
• pnpm build
• pnpm typecheck
• pnpm test
• pnpm smoke:actions-sandbox
• swift build --package-path native/macos/CuedNative -c release
• Push hook ran pnpm check:ci-local, including app quality checks and native macOS build.