@rail44.dev/goose

The file `src/events.rs` moved to `quacker-core/src/events.rs` in the quacker-core extraction (PR #312); `src/events.rs` no longer exists at the top level. Four docs still point at the old path. Update each path reference to the new location so the navigation pointer is correct:

- `docs/atproto-publish-spike.md` line ~18 — "Source: `src/events.rs` (the `Event` enum), ...".
- `docs/e2e-implementation-design.md` line ~106 — "既存の `EventEnvelope` 構造(`src/events.rs`)は ...".
- `docs/embedding-axes-spike.md` line ~44 — "... verbatim で運ぶ(`src/events.rs`)。".
- `docs/push-notification-spike.md` line ~250 — "`src/events.rs` — `parent_post_id` field ...".

In each, replace the path `src/events.rs` with `quacker-core/src/events.rs`. Change ONLY the path string; keep all surrounding prose (and any line-number suffixes, symbol names, etc.) byte-for-byte identical.

Constraints:
- Edit ONLY those four files. Do NOT touch any other file (the path may also appear in `.claude/dispatches/*` historical briefs and in code — all out of scope).
- This is a mechanical path update for a moved file; do not rewrite any prose or change any numbers.