feat(sim): analytical Left HUD redesign + affect channel + no-cache

Left-brain HUD look-and-feel pass (judged by eye in the sim):
- corner-bracket targeting reticles (capped arms) replace plain boxes
- translucent label chips, legible over any frame
- two sensor channels: cyan detections (with deterministic confidence
  scores) vs amber measurements (center crosshair)
- bbox-sized "ANALYSIS . L{n} . {k} OBJ" status tag, escalating with Left

Affect channel (emotions in the HUD), per
docs/superpowers/specs/2026-06-22-affect-channel-hud-design.md:
- surfaces only when BOTH knobs up; strength = min(left, right)
- stable per-scene palette, more words appear with combined strength
- soft glowing violet words on their own opacity layer (the dream
  leaking into the machine's read); math in player/alteration.py
- forest/cosmos/abyss palettes in the manifest; 5 new unit tests

Simulator no-cache middleware so by-eye iteration never serves a stale
app.js / api response (fixes the latent "plan has affect but clip.affect
empty" stale-/api/clips bug).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_player_alteration.py

@@ -3,6 +3,7 @@ import pytest
 from hef.selection import Coordinate
 from player.alteration import (
     DEFAULT_CALIBRATION,
+    AffectOverlay,
     AnalyticalOverlay,
     Calibration,
     ColorGrade,
@@ -48,6 +49,45 @@ def test_left_and_right_stack_not_cancel():
     assert plan.restyle.variant == 4
 
 
+def test_affect_needs_both_knobs_up():
+    # affect-channel design (session 0013): emotion-words surface only when BOTH
+    # the Left and Right knobs are up — either at 0 means no affect at all.
+    assert plan_alteration(_coord(left=4, right=0)).affect.strength == 0
+    assert plan_alteration(_coord(left=0, right=4)).affect.strength == 0
+    assert plan_alteration(_coord(left=4, right=0)).affect.intensity == 0.0
+    assert plan_alteration(_coord(left=0, right=4)).affect.intensity == 0.0
+
+
+def test_affect_strength_is_the_smaller_knob():
+    # strength = min(left, right) — the smaller knob gates the channel.
+    assert plan_alteration(_coord(left=2, right=4)).affect.strength == 2
+    assert plan_alteration(_coord(left=4, right=2)).affect.strength == 2
+    assert plan_alteration(_coord(left=4, right=4)).affect.strength == 4
+    assert plan_alteration(_coord(left=3, right=1)).affect.strength == 1
+
+
+def test_affect_intensity_scales_with_strength_over_full_scale():
+    for lo in range(5):
+        plan = plan_alteration(_coord(left=lo, right=4))
+        assert plan.affect.intensity == pytest.approx(lo / 4)
+    assert plan_alteration(_coord(left=4, right=4)).affect.intensity == 1.0
+
+
+def test_affect_intensity_honors_overlay_gain():
+    # affect rides the same overlay_gain as the analytical HUD it belongs to.
+    cal = Calibration(overlay_gain=0.5)
+    assert plan_alteration(_coord(left=4, right=4), cal).affect.intensity == pytest.approx(0.5)
+    clamp = Calibration(overlay_gain=10.0)
+    assert plan_alteration(_coord(left=4, right=4), clamp).affect.intensity == 1.0
+
+
+def test_affect_active_implies_non_identity():
+    # min(left,right) > 0 implies left > 0, so an active affect plan is never identity.
+    plan = plan_alteration(_coord(left=2, right=3))
+    assert plan.affect.strength == 2
+    assert not plan.is_identity
+
+
 def test_light_pole_grades_warm_positive_tone():
     plan = plan_alteration(_coord(light=4))
     assert plan.grade.tone == 1.0
@@ -117,6 +157,7 @@ def test_render_plan_to_dict_round_trips_the_numbers():
     assert d == {
         "grade": {"tone": -1.0},
         "overlay": {"level": 4, "intensity": 1.0},
+        "affect": {"strength": 2, "intensity": 0.5},
         "restyle": {"variant": 2},
         "is_identity": False,
     }