feat(core): #77 ship canonical Position/Body/Collider from ludic.core package

The engine-owned esys_move (#65) reads Position/Body/Collider/Solids by name,
but no package defined them — every game and example re-declared identical
bundles by hand. Ship them as the source package ludic.core; games import
instead of copy-pasting, and extend by composition (attach their own
components on the same model). AOT → compiles into the consumer's ECS with no
seam; integer + Q16.16 deterministic. Adds examples/library/core_components
(driven by esys_move, composed with a game Health component) as a
controller_case (104/0).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/ludic.core/components.ludic

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+# components.ludic — the canonical engine-ABI components (#77).
+#
+# These are the exact bundles runtime/native/systems_move.ludic (#65) reads by
+# name. Import this file instead of re-declaring them, and the engine-owned
+# `esys_move` system moves and collides your entities for free — declare a Body
+# (and optionally a Collider) and it is ticked in the Update phase.
+#
+# Every field is defaulted so a game overrides only what it needs, and any field
+# the move system does not find on an entity no-ops cleanly. Extend by
+# *composition*: attach your own components (Health, Sprite, an AI brain) on the
+# same model next to these; nothing here needs subclassing.
+
+# The world anchor: integer pixels. This is the *rendered* location — a
+# framebuffer pixel is the smallest drawable unit — so it stays integer. Sub-pixel
+# motion accumulates in Body.rx/ry (Q16.16) and only the whole-pixel carry reaches
+# Position (see docs/RFC-POSITION-TYPES.md, #78).
+property Position { x: int = 0, y: int = 0 }
+
+# A moving body: Q16.16 velocity, optional gravity, engine-owned sub-pixel
+# accumulators, and the polled contact outputs the move system writes each frame.
+#   policy 0 = platformer (gravity applies)   policy 1 = top-down (no gravity)
+# on_ground / hit_wall / hit_ceiling and the optional contact normal hit_nx/hit_ny
+# are OUTPUTS: read them in a handler to raise your own landing / bonk events
+# (the SpriteAnim.event_fired pattern — polled flags, no engine coupling).
+property Body {
+  vx: fixed = 0.0, vy: fixed = 0.0,
+  gravity: fixed = 0.0, max_fall: fixed = 0.0,
+  rx: fixed = 0.0, ry: fixed = 0.0,
+  policy: int = 0,
+  on_ground: int = 0, hit_wall: int = 0, hit_ceiling: int = 0,
+  hit_nx: int = 0, hit_ny: int = 0
+}
+
+# An axis-aligned box off the Position anchor. A solid Collider resolves swept-AABB
+# collisions; a trigger (is_trigger = 1) reports overlap without resolving. layer /
+# mask are collision bitmasks (0 = all); one_way = 1 is a platform that blocks only
+# a downward landing. hit / entered / exited are trigger OUTPUTS.
+property Collider {
+  w: int = 0, h: int = 0, offx: int = 0, offy: int = 0,
+  is_trigger: int = 0, one_way: int = 0, layer: int = 0, mask: int = 0,
+  hit: int = 0, entered: int = 0, exited: int = 0
+}
+
+# Optional single config entity that turns the tile-grid broadphase on: solids are
+# read from the Map.* tilemap. tile > 0 sets the tile size in px; wall is the solid
+# glyph; oneway is an optional one-way-platform glyph (0 = none).
+property Solids { tile: int = 0, wall: int = 0, oneway: int = 0 }

packages/ludic.core/package.ludic

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+# ludic.core — the canonical engine-ABI components (#77).
+#
+# The engine-owned movement system (runtime/native/systems_move.ludic) reads
+# Position / Body / Collider / Solids *by name* through the reflection ABI, but
+# no package defined them — so every game and every example re-declared identical
+# `property Position/Body/Collider` bundles by hand, copy-pasting the engine ABI.
+# That is exactly the kind of thing a game developer should never hand-write.
+#
+# This package ships those bundles as the one canonical definition. A game
+# imports them instead of copy-pasting, and extends by *composition* — attach
+# your own components alongside on the same model; the engine still resolves
+# Position/Body/Collider by name, and any field a game does not need simply keeps
+# its default. It is an ordinary source package: AOT means the properties compile
+# straight into the consumer's compile-time ECS with no ABI seam, and everything
+# stays integer + Q16.16 deterministic (lockstep / replay / world_save hold).
+package "ludic.core"
+version "0.1.0"
+kind source
+provides "Position"
+provides "Body"
+provides "Collider"
+provides "Solids"