refactor(hooks): drop runtime shadow types and tighten the executor

[dgageot]

What

pkg/hooks/config.go had grown a 12-events-listed-in-four-places translation layer on top of pkg/hooks.Config/Hook/MatcherConfig — pure shadow copies of latest.HooksConfig/HookDefinition/HookMatcherConfig that existed only to attach Hook.GetTimeout() and a typed HookType. This series replaces the shadow with type aliases, deletes the conversion code, and tightens a few executor types along the way.

The four commits are independently buildable so they can be reviewed in order.

Commits

1. refactor(hooks): drop runtime shadow types in favor of latest aliases — pkg/hooks.Config/Hook/MatcherConfig become type aliases for the persisted types. Deletes FromConfig, the two converter helpers, and the duplicate Config.IsEmpty. Moves GetTimeout to latest.HookDefinition so both names share it through the alias. Softens HookType to a string alias to keep existing test fixtures compiling without conversion churn. Net −63 lines.

2. refactor(hooks): tighten executor types and dispatch test — five small, related cleanups now that the types are unified:

   • drop matcher.raw ("" and "*" already short-circuit to a nil regexp); matches() collapses to one return statement
   • merge hookResult and HandlerResult (they had parallel field names); hookResult now embeds HandlerResult and only adds err
   • extract parseStdoutJSON so the JSON-on-stdout fallback isn't three nested ifs inside runHook
   • replace the contextEvents map with EventType.consumesContext() (same four events, reads as a question about the event)
   • move HookType + constants from types.go to config.go next to the Hook alias they describe
   • compress dispatch_test.go's per-event fixtures into one onlyHooks map literal iterated twice

3. fix(hooks): preserve stderr and exitCode in hookResult error paths — fixes a regression introduced in commit 2: when runHook hit a timeout or handler error, returning a fresh hookResult{err:...} silently dropped the handler-captured Stderr that aggregate reads to build the PreToolUse fail-closed message. Restores Stderr and ExitCode = -1 on both error returns.

4. fix(hooks): also preserve stdout in failed-hook results, pin contract — tightens commit 3: replaces the explicit HandlerResult{Stderr: ..., ExitCode: -1} literal with a small markFailed closure that mutates the already-built r in place. This preserves both Stdout and Stderr (matching pre-refactor behaviour exactly) and is robust to future fields on HandlerResult. Adds TestExecutorHandlerErrorPreservesStderr to pin the contract — this test fails against commit 2's code, so it would have caught the original regression.

Net effect

• pkg/hooks/config.go shrinks from a 12-event translation layer to a 44-line file containing only type aliases and HookType constants
• The 12-event listing now exists in exactly two places: the HooksConfig struct itself (which owns IsEmpty and validate) and compileEvents in the executor — down from five
• Adding a new event is one field on latest.HooksConfig plus one line in compileEvents
• Public API surface (hooks.Config, hooks.Hook, hooks.MatcherConfig, hooks.HookType, all the constants) is unchanged — every existing struct literal, YAML key, and runtime path still works
• New test TestExecutorHandlerErrorPreservesStderr pins the PreToolUse fail-closed stderr contract that previously had no coverage

Verified

• mise lint — 0 issues
• mise test — 97 packages green
• Rebased on top of current origin/main (resolved a conflict with the recent buildHooksExecutors extraction; the change there is just dropping the now-unnecessary hooks.FromConfig wrapper)