refactor(web): replace manual useEffect+fetch with SWR to eliminate set-state-in-effect lint bypasses

[nocoo]

Closes #135

Summary

Introduces SWR as the data-fetching layer for the web dashboard, replacing all manual useEffect + fetch + setState patterns. This eliminates 33 eslint-disable react-hooks/set-state-in-effect directives across 27 files.

Changes

1. Add SWR + shared fetcher.ts
2. Migrate use-fetch-data.ts to SWR internally (keeps same return interface)
3. Migrate 10 data-fetching hooks to SWR
4. Migrate 16 page/component-level fetches to SWR
5. Fix review findings: clear optimistic overrides after revalidation, clear sticky mutation errors

Review Notes

• R1 Codex review found 2 issues (optimistic override stale state, sticky mutationError) — both fixed in commit 5
• R2 review confirmed fixes; noted a theoretical race condition in org page concurrent operations (non-blocking, SWR auto-revalidation self-corrects)