refactor: unify duplicate Logger interfaces into single canonical type (#14)

* refactor: unify duplicate Logger interfaces into single canonical type

23 files had local Logger/StoreLogger/PluginLogger/PipelineLogger/RunnerLogger/ExtractorLogger/TriggerLogger
interface definitions with identical shapes ({debug?, info, warn, error}).

Replace all with imports from the canonical `Logger` in `src/core/types.ts`:
- 17 files: local `interface Logger` → `import type { Logger }`
- 6 files: named variants (StoreLogger, PluginLogger, etc.) → `type X = Logger` alias

Two intentionally different interfaces are preserved:
- `CheckpointLogger` (only info + optional warn) — different contract
- `ensure-hook-policy.ts` Logger (no error) — different contract

Net: -120 lines, zero behavioral change.

Signed-off-by: yuanrengu <heyonggang0811@126.com>

* docs: update Logger JSDoc to reflect canonical relationship

StoreLogger, PluginLogger, etc. are now type aliases of Logger, not the
other way around. Update the comment to clarify this inverted relationship.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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Signed-off-by: yuanrengu <heyonggang0811@126.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>