refactor(button): consolidate button styles into Button.astro

Extends Button.astro with a center prop, native <button> element support
(type, disabled, aria-describedby), harmonised padding (.65rem), and
transition. Removes global .button, .button-small, .button-light, and
.button-center rules from components.css, layout.css, and typography.css.
Converts all inline class="button" usages across Header, HomeHero,
HomeFinancialHelp, HomeServicesIntro, FormShell, TeamPage, CareersPage,
and FaqPage to the <Button> component. Updates three scoped style
selectors to :global() to reach the child component's elements.

www/src/styles/typography.css

@@ -11,7 +11,7 @@ h3 { font-size: clamp(1.8rem, 3.4vw, 2rem); }
 h4 { font-size: clamp(1.5rem, 3vw, 1.8rem); }
 a, a:visited { color: var(--color-accent-strong); text-decoration: none; }
 a:hover, a:active { color: var(--color-accent); }
-a.button { color: var(--color-primary) }
+
 
 .eyebrow {
   margin: 0;