chore: import upstream snapshot with attribution

test/fixtures/jsonl/basic.jsonl

@@ -0,0 +1,2 @@
+{"type":"user","uuid":"u1","sessionId":"sess-basic","timestamp":"2026-04-17T10:00:00.000Z","cwd":"/Users/alice/project","message":{"role":"user","content":[{"type":"text","text":"Fix the login bug"}]}}
+{"type":"assistant","uuid":"a1","sessionId":"sess-basic","timestamp":"2026-04-17T10:00:05.000Z","message":{"role":"assistant","content":[{"type":"text","text":"Looking into it now."}]}}

test/fixtures/jsonl/errors.jsonl

@@ -0,0 +1,4 @@
+{"type":"user","uuid":"u1","sessionId":"sess-err","timestamp":"2026-04-17T12:00:00.000Z","cwd":"/tmp/x","message":{"role":"user","content":[{"type":"text","text":"Run tests"}]}}
+not-valid-json-line
+{"type":"assistant","uuid":"a1","sessionId":"sess-err","timestamp":"2026-04-17T12:00:01.000Z","message":{"role":"assistant","content":[{"type":"tool_use","id":"t1","name":"Bash","input":{"command":"npm test"}}]}}
+{"type":"user","uuid":"u2","sessionId":"sess-err","timestamp":"2026-04-17T12:00:02.000Z","message":{"role":"user","content":[{"type":"tool_result","tool_use_id":"t1","content":"exit 1","is_error":true}]}}

test/fixtures/jsonl/tool-use.jsonl

@@ -0,0 +1,4 @@
+{"type":"user","uuid":"u1","sessionId":"sess-tool","timestamp":"2026-04-17T11:00:00.000Z","cwd":"/Users/bob/repo","message":{"role":"user","content":[{"type":"text","text":"List the files"}]}}
+{"type":"assistant","uuid":"a1","sessionId":"sess-tool","timestamp":"2026-04-17T11:00:02.000Z","message":{"role":"assistant","content":[{"type":"tool_use","id":"toolu_1","name":"Bash","input":{"command":"ls"}}]}}
+{"type":"user","uuid":"u2","sessionId":"sess-tool","timestamp":"2026-04-17T11:00:03.000Z","message":{"role":"user","content":[{"type":"tool_result","tool_use_id":"toolu_1","content":"README.md\nsrc\n"}]}}
+{"type":"assistant","uuid":"a2","sessionId":"sess-tool","timestamp":"2026-04-17T11:00:04.000Z","message":{"role":"assistant","content":[{"type":"text","text":"Two entries."}]}}