fix(store): filter unsupported chains out of read paths for addedSafes

[TenderDeve (tenderdeve)]

What it solves

Resolves: #2585

Persisted chainId-keyed slices (addedSafes, address book, undeployed Safes, pinned Safe apps, …) hold entries for chains the gateway no longer lists. Consumers that iterate the raw maps surface stale state — this was the original trigger behind the linked incident in #2584.

Maintainer guidance on the issue was to filter at READ time rather than mutate localStorage. There was already a private _sanitizeNotifiableSafes doing exactly this for push-notification registration. This PR lifts that into a shared util and starts wiring it through the rest of the read paths.

How this PR fixes it

• apps/web/src/utils/chainEntries.ts — new generic pickSupportedChainEntries(byChainId, chains) util (kept out of utils/chains.ts to avoid pulling the store-init graph back into the slice file).
• addedSafesSlice — new memoised selectAllAddedSafesOnSupportedChains(state, chains) selector.
• LocalSafesAlert (Spaces sign-in entry point) routed through the sanitised selector so the on-this-browser count stops including Safes on chains the gateway dropped.
• _sanitizeNotifiableSafes collapsed to delegate to the shared util — no behavioural change, just removes the duplicate.

First slice; the same pickSupportedChainEntries + per-slice memoised selector pattern can be extended to addressBook, undeployedSafes, pinnedSafeApps, visitedSafes, etc. in follow-ups. Doing them all in one PR would touch ~150 call sites and make review hard.

How to test it

1. Add a Safe on a chain the gateway no longer returns (or temporarily filter the chain out of the useChains mock).
2. Open the Spaces sign-in screen.
3. Before: LocalSafesAlert counts the stale-chain Safe. After: it's excluded; the count matches the actual usable list.

Unit tests cover the util's filter / no-mutation / empty-chains semantics, the new sanitised selector, and the updated alert behaviour.

Affected flows

• Spaces sign-in → LocalSafesAlert count

Blast radius

• New util file + new selector; existing public selectors untouched
• _sanitizeNotifiableSafes keeps its signature, only its body now reuses the util
• LocalSafesAlert is the only consumer migrated to the sanitised selector
• No analytics / route / persisted state / RTK Query changes
• Mobile unaffected (web-only files)

Risks / not checked

• Other consumers (useAllSafes, AddAccounts, useOnboardingSafes, DataWidget, …) still read raw selectAllAddedSafes — incremental follow-ups
• Sanitised selector is parametrised by the supported chains array; consumers must pass useChains().configs (or equivalent) for the filter to engage
• Did not test on mobile (Spaces is web-only)

Visual summary

flowchart LR
  A["addedSafes slice (persisted, chainId-keyed)"] --> B["selectAllAddedSafes"]
  B --> C["direct consumers — stale-chain entries leak through"]
  A --> D["selectAllAddedSafesOnSupportedChains(state, chains)"]
  D --> E["pickSupportedChainEntries util"]
  E --> F["LocalSafesAlert count — stale-chain Safes dropped"]

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Checklist

• I've tested the branch on mobile 📱 — n/a, web-only files
• I've documented how it affects the analytics (if at all) 📊 — none
• I've written a unit/e2e test for it (if applicable) 🧑‍💻 — util, sanitised selector, alert
• I've listed affected flows and blast radius, and named what I did not verify 🎯

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[Zalens (Zalens)]

Thanks TenderDev, I am closing this one. LocalSafesAlert was deleted in #8271 (20 Jul), and that was the only part here with a visible effect; the rest has no consumer.