image parity: imsd 0.3.0 (pinned public commit) + callaudioshim + modem-daemon override

imsd turns out to be fully public already (0.2.7 snapshot + emergency
stage 1 + the make build path) - no tag needed, same git-archive dance as
the kernel. callaudioshim was a load-bearing unpackaged home-dir script on
the phone (callaudiod replacement, working in-call mic mute); now an aport
autostarted at phase 1. kde-telephony's modem daemon autostart is hidden
via /etc/skel from the imsd package, mirroring the phone's user override.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -77,5 +77,7 @@ with the `aports/` overlay in this repository:
 - [x] Speaker-audio userspace files (`soc-fairphone-fp6-audio`: topology,
       amp config, UCM — byte-identical to the tested dev-phone set; blob
       provenance to be settled before this repo goes public)
-- [ ] imsd 0.3.0 tag (aport currently needs it published)
+- [x] imsd in the image (pinned to the public 0.3.0 commit; the phone's
+      working call stack incl. callaudioshim and the modem-daemon autostart
+      override ship as packages)
 - [ ] Nightly schedule once the first dispatched run is green