docs: fix two Copilot-flagged comment inaccuracies

- Dockerfile.base.j2: comment said libraspberrypi0 comes from
  archive.raspbian.org's `rpi` component, but the Deb822 source
  below correctly declares `Components: firmware`. Verified via
  Packages.gz on archive.raspbian.org/dists/trixie/firmware/
  binary-armhf — that's the only component shipping
  libraspberrypi0 on trixie/armhf. Comment now matches reality.

- image_builder/utils.py: Qt 5 branch comment claimed the modern
  equivalents (libgstreamer1.0-dev, libsqlite3-dev, libsrtp2-dev)
  for the dropped trixie packages were "pulled by the main viewer
  apt list above". libsqlite3-dev / libsrtp2-dev are indeed in
  that list, but libgstreamer1.0-dev is Qt 5-only and is added by
  the extend() call right below — corrected the comment to point
  there instead.

Both are pure comment changes; behavior unchanged.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docker/Dockerfile.base.j2

@@ -5,7 +5,8 @@ FROM {{ base_image }}:{{ base_image_tag }}
 # userland: libbcm_host, libmmal, libvchiq_arm) for the Qt 5 webview.
 # Trixie's archive.raspberrypi.org/main no longer ships it (replaced
 # by raspi-utils, which doesn't cover Qt's link path), so we pull it
-# from archive.raspbian.org's `rpi` component instead.
+# from archive.raspbian.org's `firmware` component instead (verified:
+# libraspberrypi0 ships there on trixie/armhf, not in `rpi`).
 #
 # Trixie's apt uses Sequoia (sqv) for signature verification and rejects
 # the standalone .public.key / .gpg.key files because their User ID

tools/image_builder/utils.py

@@ -247,9 +247,9 @@ def get_viewer_context(board: str, target_platform: str) -> dict[str, Any]:
         # repeated here. libssl1.1 is gone in trixie; the rebuilt Qt 5
         # webview archive links against libssl3 from the base image.
         # libgst-dev / libsqlite0-dev / libsrtp0-dev were dropped in
-        # trixie — modern equivalents (libgstreamer1.0-dev,
-        # libsqlite3-dev, libsrtp2-dev) are pulled by the main viewer
-        # apt list above.
+        # trixie — libsqlite3-dev and libsrtp2-dev are already in the
+        # main viewer apt list above; libgstreamer1.0-dev is Qt 5-only
+        # and is added in the extend() below.
         viewer_extra_apt_dependencies.extend(
             [
                 'libgstreamer1.0-dev',