P14-03: Prove new-PID pairs inside the roster; declare UIDs and policy pins

- tests/s2/test_new_pid_pairs.gd runs each writer/reader save-restart pair as
  two real child processes and keeps their complete output in the private
  profile, since the script-level roster runs suites without arguments.
- Commit the Godot UIDs of scripts added this session (and the pre-existing
  peeping-room scripts that lacked tracked UIDs) plus the legacy fixture's
  thumbnail import, so a private import generates nothing undeclared.
- Repin suite-policy source SHAs for test_main_dashboard (A06 HUD, palette 25)
  and test_runtime_transport (sustained outage helper); flags unchanged.
- Register the pair suite's completion marker.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/fixtures/p14-03/legacy_rush_v1/thumbnail.png.import

@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://cnde4l2e1lib7"
+path="res://.godot/imported/thumbnail.png-307ea4ea2aa92de395157267241a407e.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://tests/fixtures/p14-03/legacy_rush_v1/thumbnail.png"
+dest_files=["res://.godot/imported/thumbnail.png-307ea4ea2aa92de395157267241a407e.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1