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/handlers/collections.go

@@ -496,7 +496,8 @@ func (h *CollectionHandler) DeleteCollection(c *echo.Context) error {
 	}
 
 	if c.Request().Header.Get("HX-Request") == "true" {
-		html := `<div class="text-green-500">Collection deleted! Redirecting...</div><script>window.location.href = '/collections';</script>`
+		// CSP: no inline scripts in partials — auth_forms.ts navigates.
+		html := `<div class="text-green-500" data-redirect="/collections">Collection deleted! Redirecting...</div>`
 		return c.HTML(http.StatusOK, html)
 	}