fix(auth): login/registration forms redirect again under hash CSP

The htmx login/registration partials answered success with an inline
<script> that stashed the auth token and set window.location — refused
by hash-mode script-src (no 'unsafe-inline'), so the user saw "Login
successful! Redirecting..." and nothing else (reported from the home-
page login form; /login was equally broken). The same pattern lived in
collections.go (delete → redirect) and devices.go (token regen →
reload, whose script tag was also unclosed).

Replacement, per the AGENTS.md CSP rules:
- auth.go login/registration: the partial now carries data-auth-token +
  data-redirect (redirect is path-only — open-redirect hygiene — and
  escaped); web/src/auth_forms.ts (new, armed from main.ts on every
  page) listens for htmx:afterSwap, stashes the token, and navigates.
- collections.go delete: data-redirect, same listener.
- devices.go token regen: htmx's native HX-Refresh response header.
- The dead localStorage 'user'/'refreshToken' writes are dropped — no
  reader anywhere in web/src; only 'token' is load-bearing (19 modules).

Tripwire extension: internal/middleware/csp_go_sources_test.go scans
non-test Go sources for literal <script> tags and native on*= attributes
(hand-written files only — templ codegen is owned by the .templ scan),
verified to fire on a reintroduced probe. AGENTS.md CSP section notes
the Go-emitted-partial vector.

Verified live: home-page login form → /dashboard with token stashed and
dashboard loading clean; /register form → /dashboard; collections and
devices share the same mechanisms (data-redirect / HX-Refresh). Gates:
make test (9 pkgs incl. both tripwires), vitest 155, Playwright 20,
tsc/vp clean.

internal/middleware/csp_go_sources_test.go

@@ -0,0 +1,69 @@
+package middleware_test
+
+import (
+	"io/fs"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+// Go-source CSP tripwire.
+//
+// The templ scan lives in templates/csp_source_test.go, but htmx partials
+// can also be emitted from Go handler strings — auth.go used to answer a
+// successful login with an inline <script>window.location…</script> that
+// hash-mode CSP silently refused. This test scans the non-test Go sources
+// for the same forbidden patterns: inline script tags and native on*=
+// handler attributes in emitted HTML. Partials that need to navigate or
+// stash state use data attributes + web/src/auth_forms.ts, or htmx's
+// HX-Redirect/HX-Refresh headers.
+
+var goScriptTagRe = regexp.MustCompile(`<script`)
+
+var goHandlerAttrRe = regexp.MustCompile(
+	`on(click|error|submit|load|change|input|focus|blur|mouseover|keydown|keyup)\s*=\s*"`)
+
+func TestGoSourcesAreCSPSafe(t *testing.T) {
+	root := "../.."
+	err := filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			switch d.Name() {
+			case "node_modules", "static", ".git", "testdata", "docs":
+				return filepath.SkipDir
+			}
+			return nil
+		}
+		name := d.Name()
+		if !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
+			return nil
+		}
+		// Generated templ codegen is out of scope: its source of truth is
+		// the .templ file (scanned by templates/csp_source_test.go), and
+		// the codegen legitimately emits external <script src=…> tags.
+		if strings.HasSuffix(name, "_templ.go") {
+			return nil
+		}
+		raw, err := os.ReadFile(path)
+		if err != nil {
+			return err
+		}
+		src := string(raw)
+		for _, m := range goScriptTagRe.FindAllStringIndex(src, -1) {
+			t.Errorf("%s:%d: literal <script> in Go source — hash-mode CSP refuses inline scripts in emitted partials; use data attributes + web/src/auth_forms.ts or HX-Redirect/HX-Refresh",
+				path, 1+strings.Count(src[:m[0]], "\n"))
+		}
+		for _, m := range goHandlerAttrRe.FindAllStringIndex(src, -1) {
+			t.Errorf("%s:%d: native on*= handler attribute in Go source — CSP hash-mode refuses it; use Alpine bindings or delegated listeners",
+				path, 1+strings.Count(src[:m[0]], "\n"))
+		}
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+}