New gem_anim.sx adds a purely-visual per-gem pose set driven by a single
animation clock: a calm always-on idle breath (scale-pulse + bob, per-gem
phase, ramped in from rest), a selection pop, a landing squash-bounce, and
a clear pop. BoardView draws every settled gem through gem_pose_at /
gem_pose_frame; the move timeline (P6.1) and FX (P6.2) are untouched and the
input-lock semantics are unchanged (idle never locks input).
Determinism: the idle is always-on, so main reads M3TE_ANIM_TIME=<seconds>
to freeze the clock at a chosen phase (t==0 == the resting board, so the
pre-P6.3 goldens reproduce) and M3TE_SELECT=<cellIndex> to force a selection
for capture. tests/gem_pose.sx locks the t==0-rest invariant and the reaction
envelopes headlessly (fails if the idle ramp is dropped).
Goldens (deterministic capture): p6_idle_t0 (resting), p6_idle_mid (pinned
mid-breath), p6_select (selection pop on cell 3,3). Purely visual: no change
to model/score/moves/hit-testing.
Add a real logic-test gate so future pure-sx game logic fails the build on a
bad assertion:
- tests/test.sx: `expect(cond, msg)` assert helper — prints a greppable
`FAIL <file>:<line>: <msg>` and exits non-zero via process.exit on failure.
- tools/run_tests.sh: snapshot runner mirroring sx/tests/run_examples.sh; runs
each tests/<name>.sx and diffs stdout + exit code against tests/expected/.
Exits 0 iff all tests pass.
- tests/arith.sx (+ expected snapshots): seed passing sanity test.
- README.md: document both halves of the gate — logic runner and the
reproducible ios-sim build/launch sequence (with device discovery).
