feat: first-person player with Enhanced Input

AGigLineCharacter: 1.75 m capsule, 1.60 m eye camera, 4 m/s walk, mouse look
scaled in degrees per second (no double DeltaTime), jump. Loaded ahead of a
Blueprint so the demo is playable with no assets wired by hand.

Tools/ue_create_input_assets.py builds /Game/Input headlessly: five 1D actions
and an 11-mapping context. One action per direction instead of per-key modifiers,
because modifier objects do not survive the save path here: a mapping's modifier
array serialises None, and dimensioning a 2D move with per-key axis masks would
need exactly those modifiers. The cost is four action assets rather than two.

Also adds a fourth review camera at eye height and documents it; its approval is
pending.

Screenshots/README.md

@@ -44,6 +44,27 @@ its baked skin material and A-pose bind.
 Close three-quarter view of the cube row. Each cube is exactly 1 m — use it
 to judge scale against the character.
 
+## review-03-first-person.png — generated 2026-11-07, approval: ☐ pending
+
+![Third-person shot from a player's eye line looking across the review floor: the MPFB character at origin (spawn point), one red cube behind it, sky and horizon behind](review-03-first-person.png)
+
+New shot for the first-person player work. Camera is at 165 cm — the player's
+eye height — looking from behind and slightly south-east of the spawn point.
+It shows where the player lands (the character stands at origin, which is also
+the default spawn) and how the capsule/camera relate to the 1 m cubes.
+
+**What changed in the game since the last review:** the project now has a
+first-person `AGigLineCharacter` (1.75 m capsule, 1.60 m eye camera, 4 m/s
+walk, Enhanced Input with WASD + mouse look + jump) wired as the default pawn
+by `AGigLineGameModeBase`. Nothing visible from these cameras should differ:
+the review map spawns its own pawn-free staging, so this shot is the reference
+for the new pawn's position and eye height, not of the pawn itself.
+
+**Not shown, needs a human check:** walking, mouse look and jump can only be
+judged interactively. Launch the editor, press Play on `Test/ReviewMap`, and
+confirm W/A/S/D move in the expected directions, the mouse looks around with no
+acceleration, and Space jumps once per press.
+
 ## What to look for
 
 - **Character**: proportions, bind pose, skin material readability.