Subtree dirty-tracking with tree patches

[colemancda]

Summary

Re-evaluates only the subtree whose state actually changed, hands the interpreter a patch instead of a full root, and moves scalar prop values off the JSON path.

• Stable callback ids: callback ids are now an FNV-1a hash of the registering view's identity path plus registration ordinal, replacing generation-tagged ids. Handlers keep the same id across every evaluation, so un-patched nodes stay valid — and the recurring id-churn bugs are fixed at the root.
• Dirty paths: every state write reports the identity path of the owning view (navigation and geometry stores included).
• Re-entry anchors: during resolution, each state-install path records the outermost view of its wrapper chain plus its context, so a re-resolution reproduces parent-applied modifiers. Lazy containers mark boundaries; group-spread modifiers invalidate anchors they cover.
• ViewHost.evaluateUpdate(): returns a patch when all dirt lands at one anchored path; falls back to a full pass for first render, @Observable mutations, multi-path writes, lazy-row state, or when the subtree republished changed ancestor-visible data (title, search state, preferences).
• TreeStore.patch: splices the re-materialized subtree by node id with copy-on-spine sharing; a miss returns false and the bridge recovers with a full update.
• Lazy row invalidation: containers stamp a per-evaluation contentVersion included in the row remember key, so cached rows re-fetch exactly when their container re-evaluated.
• Typed prop transport: the bridge constructor takes a kind tag per value selecting a string slot or a 64-bit bits slot (doubles bit-cast into the long, so 63-bit callback ids and doubles both cross exactly); only array-valued props still cross as JSON text. No Json.parseToJsonElement per scalar, no string escaping on the Swift side.

Testing

• 123 SwiftUICore tests pass, including new suites for callback identity and subtree updates (patch shape, multi-write fallback, parent-modifier preservation, title-change fallback).
• Verified on the Android emulator: button taps splice only the playground subtree (confirmed via a temporary patch probe), toggle, slider drag (50%→89%), navigation push/pop, transitions and withAnimation, and searchable filtering all behave correctly on the typed transport.