fix(wire): extract Livewire bridge to /wire subpath addon

[zachiler]

Wire-bridge extraction (v0.3.0-alpha)

Moves the Livewire integration out of core into a self-contained /wire subpath addon, so the engine stays framework-agnostic and the downstream bridge can evolve on its own. Part of the v0.3.0-alpha decoupling chapter.

What changed

• New AlpineFlowWire addon (src/wire/index.ts) — registered via Alpine.plugin(AlpineFlowWire), activates through setup(canvas) only when a Livewire $wire proxy is present. Maps flow:* server→client commands to canvas methods and AlpineFlow events to $wire method calls.
• Relocated the bridge: src/core/wire-bridge.ts → src/wire/bridge.ts (core no longer imports it).
• /wire subpath is ESM-only: exports entry is types + import (alpineflow-wire.esm.js). The dead default/CDN target and lib/wire.cdn.ts were dropped — WireFlow consumes the .esm.js, never the CDN/require variant. (CDN/no-build support for the structured addons is a deliberate follow-up, not a no.)
• New public canvas API: selectNodes / selectEdges / setNodeLocked / setNodeHidden (also declared on CanvasContext). The bridge's lock/hide/select composites route through these public methods instead of reaching into internals (TDD'd).
• Addon lifecycle: setup() may return a cleanup fn, now invoked on canvas destroy.
• Types: wireEvents removed from core FlowCanvasConfig; re-declared via module augmentation inside the addon so consumers keep the type. Runtime-additive.
• CHANGELOG: added the v0.3.0-alpha section (breaking bundle change + the public selection API).

Correctness fixes found in review

• Critical (fixed): client→server forwarding was dead. The addon wrote its on<Event> wrappers to canvas._config, but core's _emit reads callbacks from the closure config (a different object — _config is a one-time stripped copy). Fix: added _liveConfig() to core returning the live closure config (not stored as reactive data, so it stays collab-safe); the addon targets it. Restores the exact pre-extraction behavior.
• Hardening: no silent version-skew regression. If this addon ever meets an older core lacking _liveConfig() (realistic — WireFlow vendors the bundle as a separate artifact), it now console.warns and skips forwarding rather than silently writing the stale copy and re-introducing the dead-forward bug.
• Selection semantics: emit-on-actual-change. selectNodes/selectEdges now emit selection-change only when the selection truly changes, at most once per call. Client listeners (and the server, if selection-change is mapped in wireEvents) observe server-driven selections, but re-issuing the same ids is a no-op that does not re-emit — so an idempotent server→client→server round-trip cannot loop. Also collapses the old clear-then-set double emit and skips unknown ids.

Known limitation (documented, not fixed)

wireEvents:{init:…} does not forward — core emits init before _initAddons() runs the wire setup(). Reordering core init is riskier than the edge case warrants (other addons rely on _container/ResizeObserver being ready first). Documented in code.

Tests

• New real-canvas integration test (wire-events-integration.test.ts) mounts flowCanvas + the wire addon + a $wire and asserts a node-click reaches $wire (fails before the _liveConfig fix, passes after). Plus tests for the version-skew warn path and the selection-change guard.
• Full suite: 3052 passing, tsc --noEmit clean.

Not in this PR

The WireFlow-side migration (vendor alpineflow-wire.esm.js + default-load it, since the bridge is baseline for WireFlow, not opt-in) happens in the wireflow repo at resync.