docs(wails): move the prose onto v3 and record Phase 7

CLAUDE.md gains a Packaging section for the four Taskfile facts the
recipes just needed — wails3 on PATH by bare name, no -ldflags on
`wails3 build`, bin/ not build/bin/, and bundling as its own step —
plus how build/'s platform metadata generates from build/config.yml and
what that refresh overwrites.

Its lifecycle, bindings, harness, events and CI sections were still
describing v2. The events one matters most: the rule to emit through
events.Emit survives, but its justification is now the weaker one, and
saying so is the point of the migration. v2's runtime.EventsEmit
log.Fatalf'd on any context not carrying the runtime; v3's emit takes
no context at all, so what is left to pin is that one emit path is what
lets emitStatus drop an unchanged payload for every caller at once.

README told a contributor to `go install wails/v2/cmd/wails` and
apt-get libgtk-3-dev/libwebkit2gtk-4.1-dev; the CLI is vendored and the
stack is GTK4 + WebKitGTK 6.0. Two comments claiming Xvfb and one
claiming frontend/wailsjs go with them.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UDCbcCZQepnpSQYJ6SxxZm

Makefile

@@ -21,10 +21,11 @@ dev-debug: setup generate clean
 	if [ -f .env ]; then set -a; . ./.env; set +a; fi; : "$${YJ_HOME:=$(DEV_YJ_HOME)}"; export YJ_HOME; YJ_LOG_LEVEL=debug PATH="$(TOOLBIN):$$PATH" go tool wails3 dev -config ./build/config.yml
 
 # ── Headless harness (plan 005) ──────────────────────────────────────
-# The same dev server `make dev` runs, minus the blocking GTK window:
-# Xvfb gives it the display it insists on, and the script returns once
-# :34115 answers.  This is the only entry point an agent can use, since
-# every other one blocks the terminal forever.
+# The same app `make dev` runs, minus the window: v3's `-tags server`
+# is a first-class headless mode that needs no display at all, so the
+# Xvfb this used to require is gone.  The script returns once :34115
+# answers.  This is the only entry point an agent can use, since every
+# other one blocks the terminal forever.
 dev-headless: ## Start the app headless in the background (SEED=<name> to seed)
 	@./scripts/dev-headless.sh $(if $(SEED),--seed $(SEED),) $(HEADLESS_ARGS)