fix(desktop): canonicalize relay URL in welcome team scoping

[BradGroux]

Summary

Changing only the formatting of a community Relay URL could cause the Desktop onboarding path to miss the existing Welcome Team and provision another one. The affected comparisons now use the shared relay URL normalizer, so scheme/host case and trailing-slash variants reuse the existing community-scoped state.

The change also migrates the exact legacy localStorage marker to its canonical key when it is first read. That prevents an existing installation from taking one final duplicate-provisioning path after upgrading. Starter-agent matching coverage now verifies that relay formatting variants still reuse the same deployed instance.

Related issue

Addresses the formatting-only subset of #5109.

This does not claim that localhost, a LAN or Tailscale IP, and a MagicDNS hostname identify the same relay. Those are distinct endpoint strings and cannot be safely collapsed by URL normalization alone. It also does not remove already-stale agent records or change the mobile agent picker, so #5109 should remain open for those broader cases.

Testing

• Focused onboarding and Welcome guide tests passed: 34 tests, 0 failures.
• The prior branch verification passed Desktop Biome, file-size, text-size, pubkey-truncation, typecheck, production build, and the full Desktop JavaScript suite.

[BradGroux]

This is the third recurring review + rebase pass for the open BradGroux PRs on block/buzz.

What this PR does

Canonicalizes the relay URL used as a community scope in the welcome-team ensured-marker storage key. The old code used the raw communityScope string directly, so a relay URL edit (trailing slash, uppercase scheme, mixed case) would orphan the marker and re-trigger welcome-team creation.

The fix imports the shared normalizeRelayUrl helper (already used elsewhere in the codebase) and applies it inside welcomeChannelEnsuredStorageKey. It also removes a local normalizeRelayUrl duplicate in welcomeGuide.ts that only trimmed and stripped trailing slashes, replacing it with the shared canonicalizer. The isAgentScopedToRelay early-return for falsy relayUrl is a correct guard added alongside the refactor.

Correctness

• The storage key now uses a canonicalized relay URL, so wss://community-a.example/, WSS://Community-A.Example/, and wss://community-a.example// all map to the same key. This prevents orphaned markers.
• The new test in welcome.test.mjs covers trailing-slash, uppercase-scheme, and double-slash variants.
• The ensureWelcomeTeam cache key construction is consistent — it normalizes before building the key string.
• No new dependencies. No unwrap/expect in production paths.

Rebase result

Already based on current main (02f640bc4). No rebase needed — 0 commits behind.

• Head SHA: 7298de0b715b10a60c661b949cfeb0e4a4ae3f1c (unchanged)
• Mergeable: ✅ MERGEABLE
• CI: DCO ✅, Semgrep OSS ✅, zizmor ✅

No code changes were made — this was a review + rebase pass only.

[BradGroux]

Portfolio review update (2026-08-09)

I reviewed this against current main at 5bf78671f45178f8de02ba18d3d321cbbf19cd1f and the newer discussion on #5109. The formatting bug is still real, but the original Fixes #5109 scope was too broad: URL canonicalization cannot prove that localhost, IP, and MagicDNS endpoints are the same relay, and this PR does not clean stale identities or change the mobile picker.

I rebased the branch, added migration of the exact legacy Welcome marker, strengthened starter reuse coverage across URL formatting variants, and rewrote the PR description to state the narrower scope. Focused onboarding and Welcome guide tests pass (34/34). The current head is 582fb6332f4f3c6b31fd647b3740ddfbefec35e9; #5109 should remain open for the broader identity and cleanup work.

[BradGroux]

Portfolio rebase and review update (2026-08-11)

Rebased onto main at 7e6e9c547 (2026-08-10). No conflicts.

Still needed: The relay URL canonicalization bug in welcome team scoping is still present. The onboarding polish in #5310 and the Welcome banner fixes in #5406 and #5330 did not touch welcome.ts or welcomeGuide.ts — the localStorage key still uses the raw communityScope string without normalization, so a formatting-only change to the relay URL (e.g., trailing slash, scheme case) causes a duplicate Welcome Team.

Verification: cargo check not applicable (TS only). The PR adds a legacyWelcomeChannelEnsuredStorageKey for migration and normalizes via the shared normalizeRelayUrl helper from @/shared/lib/normalizeRelayUrl. New tests cover canonicalization and legacy key migration.