feat(template): ship Chromium by default; record product decisions

- home.packages: chromium active; mime → chromium-browser.desktop
- Decisions: markdown docs stay in-repo; PPD default confirmed
- Formatter + zram still open (explained in session, not closed)

V0: flake check --no-build green.

agent/HARDWARE-QUEUE.md

@@ -143,12 +143,10 @@ that run; leftover open items still need a pass.*
       snapshot flow, "boot an older generation (how)" fires an
       instruction notification.
 - [ ] **Open-a-file smoke (viewers + mime defaults, item 8)** — after
-      `home-update`: from yazi/Thunar, open a PDF (→ zathura, themed to
+      `nomarchy-home`: from yazi/Thunar, open a PDF (→ zathura, themed to
       the palette), an image (→ imv, NOT GIMP), a video (→ mpv);
-      `xdg-open .` on a directory → Thunar. With no browser installed,
-      clicking a link must still fall through to *something sane* (the
-      firefox.desktop entries are inert); if you've uncommented a
-      browser, links go there.
+      `xdg-open .` on a directory → Thunar; a link → **Chromium**
+      (`chromium-browser.desktop` — template default as of 2026-07-10).
 - [ ] **Update awareness** — with `nomarchy.updates.enable`, let the timer
       fire (or start the unit): indicator appears only when inputs are
       behind, notification only on count growth, click opens the upgrade