test(e2e): comprehensive e2e coverage for all UI features

[ryanbas21]

Summary

• Adds 27 new e2e tests across 17 test files, bringing total from 8 → 35 (4.4x increase)
• Adds shared inject-events.ts helper to DRY up event injection patterns
• Covers every user-facing feature that previously had zero e2e coverage

What's covered

Area	Tests	What it catches
OIDC flow annotation	1	Discovery → token → userinfo phase badges
Event persistence	1	IndexedDB rehydration across panel close/reopen
CORS detection	1	Missing CORS headers → badge rendering
Error events	2	4xx/5xx warning styling
Content script relay	1	Bridge marker + postMessage protocol
Multi-flow isolation	1	Events from different flowIds
Export JSON	1	FlowExport schema + redaction
Import/export round-trip	2	Export → import → events restored + banner; Markdown export
Event selection + inspector	4	Headers tab, OIDC tab, CORS tab, tab switching
Flow health panel	3	Diagnosis issues, collapse/expand, issue → event navigation
Per-event diagnosis	1	Diagnosis tab with issue details
Recording toggle	1	Record/pause button state
View mode switching	1	Timeline ↔ Flow ↔ Learn
Snapshots	1	Save → load → delete lifecycle
Connection status	4	OIDC detected, SDK connected, event count, flow chip
Flow view + playback	2	Rail rendering, play/pause/reset controls
Decode error resilience	1	Extension stability after malformed events

Key implementation details

• Tests needing diagnosis data inject events live (not via reload) since diagnosis is only delivered via PANEL_EVENT broadcasts, not GET_STATE rehydration
• Uses semantic locators (.tag-oidc, .tag-cors badges → ancestor .tl-row) instead of positional nth() to avoid flakiness from shared browser context state
• Content script relay test documents a known Playwright limitation where content script injection can be delayed on first navigation in persistent contexts

Test plan

• All 35 Chrome e2e tests pass (xvfb-run pnpm exec playwright test --project=chrome)
• All 319 unit tests pass (pnpm test)
• No changes to source code — tests only

🤖 Generated with Claude Code