fix: resolve Svelte 5 reactivity warnings

[ChiragAgg5k]

Summary

• Eliminates all state_referenced_locally and non_reactive_update warnings surfaced by svelte-check and the build (svelte-check now reports 0 errors, 0 warnings on this branch).
• Touches 46 Svelte files across tutorial layouts, markdoc nodes/tags, init ticket flows, blog, threads, integrations, theme provider, and shared UI primitives.

Approach

• $derived wraps top-level reads of props / data so access happens in a reactive context (e.g. ticket-card, button, noise, Storage_Image, Heading, Link, Call_To_Action, Partner, blog page, changelog entry, threads, integrations, animated text, etc.).
• untrack wraps one-time initializers where only the initial snapshot is meaningful (setContext payloads in the 17 tutorial + blog layouts, $state(...) seeded from props in scale / customize / map / threads, and the mid-CTA init block in Heading).
• Tooltip switched melt-ui config options to getters so reactivity is preserved without firing the warning.
• skills.svelte — activePill now declared with $state() (fixes non_reactive_update).
• theme provider — removed prop-default cross-references and moved derived init values into untrack blocks.

The two remaining build-time messages (vite-plugin-svelte rolldown-vite experimental and optimizeDeps.esbuildOptions deprecated) originate from plugin internals and will resolve when vite-plugin-svelte lands full rolldown support — not addressable here.

Test plan

• bun run check → 0 errors and 0 warnings
• bun run format passes
• bun run build completes without new warnings
• Spot-check affected pages locally: any docs tutorial layout, /blog, /blog/[page], /changelog/entry/*, /init/tickets/[username], /init/tickets/customize, /integrations, /threads, /threads/[id]
• Verify tooltips still open/close correctly (melt-ui getter change)
• Verify theme provider still respects system theme and persists selection

[greptile-apps]

Greptile Summary

Mechanical Svelte 5 reactivity fix across 46 files. Props computed outside reactive contexts are wrapped in $derived; one-time initializers (setContext, initial state seeds, melt-ui config objects) are guarded with untrack; and melt-ui options are converted to getter accessors. The Array.sort mutation noted in the previous review is also addressed here by switching to toSorted.

Confidence Score: 5/5

Safe to merge — changes are mechanical reactivity fixes with no behavioural regressions identified.

All 46 changes consistently apply one of three well-understood patterns ($derived, untrack, or getter accessors). untrack is used exclusively for genuinely one-time values (event dates, initial state seeds, context setup), so no reactive updates are accidentally suppressed. The previous sort-mutation concern is resolved. No P0 or P1 findings remain.

No files require special attention.

Important Files Changed

Filename	Overview
src/lib/components/Tooltip.svelte	Converts melt-ui config options to getter accessors so reactive prop values are read lazily — correct approach for melt-ui.
src/lib/providers/theme/theme.svelte	Removes prop-default cross-references and wraps initialization blocks in untrack; existing $effect blocks still reference forcedTheme prop directly so reactive behavior is preserved.
src/markdoc/nodes/Heading.svelte	Mid-CTA init block wrapped in untrack; $state(renderMidCta) mutation inside untrack is valid since untrack only suppresses dependency tracking, not state writes.
src/markdoc/nodes/Link.svelte	Correctly refactors doFollow href stripping into $derived chain; href is now a derived value rather than a mutated variable, improving correctness.
src/routes/(init)/init/tickets/[username]/+page.svelte	shareTextOptions is wrapped in untrack but references $derived ticketUrl; texts are baked-in with the initial URL value which is intentional for a one-time random selection.
src/routes/blog/+layout.svelte	setContext calls wrapped in untrack to suppress reactivity warning; semantics unchanged from before (context was always set once on mount).
src/routes/(marketing)/(components)/(ai-animations)/skills.svelte	activePill switched to $state()! to fix non_reactive_update warning; the non-null assertion is a standard Svelte 5 pattern for DOM bindings that are populated before first use.
src/routes/threads/+page.svelte	threads state seeded with untrack(() => data.threads); correct because the local state is independently mutated by search/filter handlers that fetch fresh data themselves.
src/routes/(marketing)/(components)/scale.svelte	localStats and originalNumbers seeded with untrack; correct since they represent one-time animation start values, not reactive projections of stats.

_{Reviews (2): Last reviewed commit: "use toSorted to avoid mutating data.filt..." | Re-trigger Greptile}