Two workflow guards had drifted from the code they describe, so
`scripts/ci_guard_checks.sh` failed on a clean tree.
The Flutter release-tag pin moved out of build.yml into the shared
setup-flutter-git composite action, but the checker read that action
from a fixed repository path while its test mutated a workflow fixture.
The mutation could not reach the checker, so the rejection test asserted
against an unmodified run. The checker now resolves the action beside
the workflow it is given, and the test materialises a `.github` tree so
the pin is genuinely exercised.
The script-test roster likewise moved into ci_guard_checks.sh, which
discovers `scripts/test_*.py` by glob; the dispatch guard still expected
each one to be named explicitly in ci_checks.sh and ci.yml. It now reads
that glob and checks both aggregates delegate to the shared roster.
Consolidates duplicated logic behind shared implementations — paginated
grid tabs, focus chrome, cached remote stores, sheet selection columns,
the server artifact store and a test fixture layer — and removes code
that had become unreachable. Net reduction of about 5,500 lines with no
behaviour change.
Where a fix had landed separately in code that moved into a shared
helper, the fix was re-applied inside the helper rather than left behind
in the copy that went away.
Introduces shared seams for paginated views, D-pad reorder, media control
routing, async singletons and the device method channel, then points the
open-coded copies at them.
Also removes unused models and duplicated provider/server plumbing, folds
the twice-implemented artifact store in the server, and factors the
repeated Flutter toolchain prologue in CI into a composite action.
edde746