fix: persist filter and tab state on back-navigation (#871)

[aliangm]

Summary

Closes #871. Filter and inner-tab selections across several pages were stored in local useState, so navigating to a detail page and pressing browser Back silently reset them to the default. This swaps those call sites onto a shared sessionStorage-backed hook so selections survive the unmount/remount cycle but still reset when the tab is closed.

• New shared hook: src/hooks/useSessionStoredState.ts — useState-shaped API backed by sessionStorage, with a type-guard parameter so stale values from older builds fall back to the default safely.
• Replaced useState with useSessionStoredState at every call site listed in the issue, using the existing feature:field storage-key convention.

Call sites converted

Location	Storage key
Watchlist → Repos status filter	watchlist:repos:statusFilter
Watchlist → PRs status filter	watchlist:prs:statusFilter
Miner profile → Open Issues "Mine" filter	miner:openIssues:mineFilter
Miner profile → Open Issues "Others" filter	miner:openIssues:otherFilter
Repository → Contributors program toggle	repository:contributors:programTab
Repository → Issues filter	repository:issues:filter
PR details inner tab	pr:detailsTab
Issue details inner tab	issue:detailsTab

MinerIssuesTable.tsx was intentionally left alone — it already persists via URL search params.

Test plan

For each row above: set a non-default filter/tab → click an item → press browser Back → confirm the selection is retained.

• Watchlist → Repos: select Active → open a repo → Back → still Active
• Watchlist → PRs: select Merged → open a PR → Back → still Merged
• Miner profile → Open Issues: change Mine + Others filters → open an issue → Back → both retained
• Repository → Contributors: switch to Issue Discovery → open a miner → Back → still on Issue Discovery
• Repository → Issues: select Closed → open an issue → Back → still Closed
• PR details: switch to Files or Conversation tab → open another PR → Back → tab retained
• Issue details: switch to Submissions tab → open another issue → Back → tab retained
• Close the tab and reopen the app → all selections reset to defaults (sessionStorage scope)
• npm run build and npm run lint pass

[ventura-oss]

Could you please resolve the merge conflicts so we can proceed with the review?