chore(brand): swap header logo to a real svg + ship favicons for portal-admin (#106)

## Summary

Two related brand-asset cleanups, bundled per request:

### portal-shell — header logo
- Replace [`apf-small.png`](apps/portal-shell/public/logos/) (a 7.6 KB raster we'd extracted from the original PNG-in-SVG and re-encoded through sharp) with [`apf-logo.svg`](apps/portal-shell/public/logos/apf-logo.svg) — an actual 1024×1024 vector export (2.1 KB). Sharper at any density, smaller payload, no rasterisation artefacts when zoomed.
- [`header.html`](apps/portal-shell/src/app/components/header/header.html) swaps `<img src=…>` accordingly.
- The wide-format `apf-portal.svg` stays in place for future surfaces (login splash, etc.).

### portal-admin — favicons + PWA manifest
Mirrors what PR #84 did for `portal-shell`:
- Copy the six favicon images (`favicon.ico`, `favicon.svg`, `favicon-96x96.png`, `apple-touch-icon.png`, `web-app-manifest-{192,512}.png`) into [`apps/portal-admin/public/favicons/`](apps/portal-admin/public/favicons/). Single visual identity across the two apps.
- Customise [`site.webmanifest`](apps/portal-admin/public/favicons/site.webmanifest) for admin: `name: "APF Portal Admin"`, `short_name: "Admin"`. Everything else (icons, theme-color, display) stays identical to portal-shell's manifest.
- Wire the `<link>` block + `<meta name="theme-color">` in [`apps/portal-admin/src/index.html`](apps/portal-admin/src/index.html).
- Remove the obsolete top-level `apps/portal-admin/public/favicon.ico` — now under `favicons/`, served via `<link rel="shortcut icon">`.

## Decision worth flagging

**Assets duplicated rather than shared via a lib.** Both apps ship their own copy of the 7 favicon files (~120 KB binary each). The alternative — a `shared-assets` (or extended `shared-tokens`) lib with the assets glob copied into each app's `dist/` at build time — is the architecturally tidier path, but introduces a build-config change with no real payoff at our scale. Revisit if a third surface (e.g., a future static landing page) ends up needing the same set.

## Verification

- `nx run-many -t lint test build --projects=portal-shell,portal-admin` — green.
- Both `dist/apps/{portal-shell,portal-admin}/browser/{en,fr}/favicons/` ship the seven expected files.
- Admin's emitted `site.webmanifest` carries `"name": "APF Portal Admin"`.
- Admin's emitted `index.html` carries the full `<link>` block + `theme-color` meta.
- Portal-shell ships `apf-logo.svg` in its `logos/` folder per locale; `apf-small.png` is gone.

## Test plan

- [x] Lint + test + build green.
- [x] Built outputs spot-checked (assets ship, manifest text correct, index.html wired).
- [ ] Manual: `nx serve portal-shell` → header shows the new SVG logo crisp at 1x / 2x / 3x DPR.
- [ ] Manual: `nx serve portal-admin` → tab favicon visible, dev tools → Application → Manifest shows "APF Portal Admin" with no errors.
- [ ] Manual: install portal-admin as a PWA from a Chromium browser → the install dialog reads "Install APF Portal Admin", home-screen icon uses the same family as portal-shell.

---------

Co-authored-by: Julien Gautier <julien.gautier@apf.asso.fr>
Reviewed-on: #106

apps/portal-admin/public/favicons/site.webmanifest

@@ -0,0 +1,21 @@
+{
+  "name": "APF Portal Admin",
+  "short_name": "Admin",
+  "icons": [
+    {
+      "src": "/favicons/web-app-manifest-192x192.png?v=20260511",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "maskable"
+    },
+    {
+      "src": "/favicons/web-app-manifest-512x512.png?v=20260511",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "maskable"
+    }
+  ],
+  "theme_color": "#ffffff",
+  "background_color": "#ffffff",
+  "display": "standalone"
+}

apps/portal-admin/src/index.html

@@ -5,7 +5,17 @@
     <title>APF Portal Admin</title>
     <base href="/" />
     <meta name="viewport" content="width=device-width, initial-scale=1" />
-    <link rel="icon" type="image/x-icon" href="favicon.ico" />
+
+    <!-- Favicons + PWA manifest. Same image assets as portal-shell —
+         single visual identity across the apps — with an admin-
+         specific webmanifest so the PWA install banner reads "APF
+         Portal Admin" / "Admin" instead of the portal-shell name. -->
+    <link rel="icon" type="image/svg+xml" href="favicons/favicon.svg" />
+    <link rel="icon" type="image/png" sizes="96x96" href="favicons/favicon-96x96.png" />
+    <link rel="shortcut icon" href="favicons/favicon.ico" />
+    <link rel="apple-touch-icon" sizes="180x180" href="favicons/apple-touch-icon.png" />
+    <link rel="manifest" href="favicons/site.webmanifest" />
+    <meta name="theme-color" content="#ffffff" />
   </head>
   <body>
     <app-root></app-root>

apps/portal-shell/public/logos/apf-logo.svg

@@ -0,0 +1 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?><!-- Generator: Gravitdesign.com --><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" style="isolation:isolate" viewBox="0 0 1024 1024" width="1024pt" height="1024pt"><defs><clipPath id="_clipPath_B4TZ570FigxU4c50hle9QrZwbv6YvFBZ"><rect width="1024" height="1024"/></clipPath></defs><g clip-path="url(#_clipPath_B4TZ570FigxU4c50hle9QrZwbv6YvFBZ)"><path d=" M 302.7 566.118 C 355.817 515.422 427.036 483.173 501.691 480.62 C 626.026 477.14 721.654 557.185 738.018 669.829 C 734.571 656.604 628.618 409.16 302.701 566.118 L 302.7 566.118 Z " fill="rgb(247,169,25)"/><g><path d=" M 732.849 505.91 C 675.421 450.11 499.114 228.071 514.048 161.831 C 530.416 89.558 636.371 30.51 735.43 0 C 719.64 2.552 706.724 5.104 694.661 8.585 C 586.122 37.355 472.984 99.302 454.893 175.868 C 439.96 241.297 498.247 315.31 562.572 378.65 C 584.25 400.069 569.598 402.126 540.415 406.219 C 515.859 409.664 481.014 414.554 448.867 433.637 C 527.084 402.036 655.737 470.669 711.434 500.382 C 735.478 513.208 745.922 518.782 732.849 505.91 L 732.849 505.91 Z " fill="rgb(18,84,108)"/><path d=" M 711.885 266.354 C 737.15 226.331 785.688 206.494 821.289 222.039 C 856.897 237.816 865.799 283.06 841.394 323.894 C 816.989 363.917 768.451 384.102 732.85 368.325 C 697.242 352.78 687.774 307.538 711.885 266.354 Z " fill="rgb(18,84,108)"/><path d=" M 307.282 582.591 C 617.41 441.409 727.668 675.86 732.836 700.109 C 735.416 720.173 735.416 742.1 731.969 763.679 C 711.878 907.414 578.07 1024 433.052 1024 C 288.045 1024 187.249 907.414 207.353 763.679 C 217.694 693.146 255.022 629.459 307.282 582.591 L 307.282 582.591 Z  M 450.565 937.11 C 546.769 937.11 636.357 859.614 649.278 763.679 C 663.344 668.089 595.583 590.364 499.101 590.364 C 467.005 590.364 435.702 598.966 407.73 613.965 C 388.702 624.169 371.215 637.334 356.069 652.766 C 326.553 682.839 305.925 721.522 300.1 763.679 C 286.323 859.614 354.084 937.11 450.566 937.11 L 450.565 937.11 Z " fill-rule="evenodd" fill="rgb(18,84,108)"/></g></g></svg>

apps/portal-shell/src/app/components/header/header.html

@@ -8,7 +8,7 @@
       [class.justify-center]="collapsed()"
     >
       <img
-        src="logos/apf-small.png"
+        src="logos/apf-logo.svg"
         alt=""
         aria-hidden="true"
         width="36"