Add roaster (machine) management, mobile header-tools redesign, and profile pictures

Machines:
- roasters table + actual_roasts.roaster_id (migrations 009): per-user
  machines with a default; uploads attach to the default roaster and are
  reassignable from the roast detail view
- Learning is now per machine: /api/roaster-profile scopes to a roaster
  (default when unspecified) and applies the user's override tweaks
  (milestone temps, TP time, pace factor) on top of learned medians
- /roasters page: machine list + analysis report showing learned vs
  applied values with editable tweaks, typical RoR, and a plain-language
  list of the adjustments applied to plans; planner honors a manual pace
  override; evaluations use the roast's own machine profile

Mobile header redesign:
- The planner's header tools collapse behind a single 'Tools ▾'
  disclosure (dropdown card) at ≤720px, keeping the fixed three-row
  mobile header with no wrapped or scrolling button rows; desktop
  renders inline via display:contents (same DOM, same handlers)

Profile pictures:
- users.avatar (migration 010) + PUT/GET/DELETE /api/account/avatar;
  client-side centre-crop resize to 128px JPEG; avatar shows in the nav
  chip on every page; included in full backups

Co-Authored-By: Claude Fable 5 <[email protected]>

public/js/nav.js

@@ -10,6 +10,7 @@ const NAV_GROUPS = [
 		items: [
 			{ href: "/app", icon: "◐", label: "Planner" },
 			{ href: "/roasts", icon: "∿", label: "Roasts" },
+			{ href: "/roasters", icon: "♨", label: "Machines" },
 			{ href: "/inventory", icon: "▥", label: "Green lots" },
 			{ href: "/cupping", icon: "◒", label: "Cupping" },
 		],
@@ -112,6 +113,19 @@ export function initSideNav() {
 	return { closeMobileNav };
 }
 
+/** Renders a user's avatar into an element: their profile picture when set, else initial. */
+export function applyAvatar(el, user, cacheBust = false) {
+	if (user.hasAvatar) {
+		el.textContent = "";
+		el.style.backgroundImage = `url("/api/account/avatar${cacheBust ? `?t=${Date.now()}` : ""}")`;
+		el.style.backgroundSize = "cover";
+		el.style.backgroundPosition = "center";
+	} else {
+		el.style.backgroundImage = "";
+		el.textContent = user.email.charAt(0).toUpperCase();
+	}
+}
+
 /** Populates the nav's user chip and admin link; redirects to /login when signed out. */
 export async function loadNavUser() {
 	const response = await fetch("/api/auth/me");
@@ -123,7 +137,7 @@ export async function loadNavUser() {
 	const emailEl = document.getElementById("account-email");
 	if (emailEl) emailEl.textContent = user.email;
 	const avatarEl = document.getElementById("nav-user-avatar");
-	if (avatarEl) avatarEl.textContent = user.email.charAt(0).toUpperCase();
+	if (avatarEl) applyAvatar(avatarEl, user);
 	if (user.role === "admin")
 		document.getElementById("nav-admin")?.classList.remove("hidden");
 	return user;