feat(stdlib): namespaced standard library (issue #2)

Implement the bulk of the namespaced-stdlib proposal (workshopsoft/ludic#2):
156 namespace methods across Math, Text, List, Ease, Collide, World, Net,
Sys, Save, Mem, extended Screen, Color functions, extended Random, and Time.
All deterministic fixed-point; self-hosting (C-free bootstrap fixpoint holds).

Compiler (selfhost/):
- Math.*: sqrt/sin/cos/tan/atan2/asin/acos (fixed-point runtime prelude —
  bit-by-bit isqrt, 256-entry interpolated sine table, Ross atan2), plus
  hypot/dist/dist2/deg_to_rad/rad_to_deg/posmod/wrap/ping_pong/snapped/
  move_toward/smoothstep/lerp/remap/sign/floor/ceil/round.
- Text.* (complete): upper/lower/trim/repeat/pad, split/join/replace,
  and the libc-backed queries.
- List.* (complete): insert/remove_at/remove/sort plus the earlier ops.
- Ease.* (in/out/in_out/back/bounce) and Collide.* (rects/point_rect/
  circles/rect_circle).
- Phase 3: World/Net/Sys/Save namespaced over the bare builtins (byte-
  identical IR) and Mem.* (bytes/words/copy/fill/peek/poke).
- Screen.* extended (line/circle/fill_circle/triangle/fill_triangle via new
  runtime primitives; sprite/sprite_scaled aliases), Color.* functions,
  Random.* (value/int/sign), Time.* (frame/delta/elapsed/now — new
  game-loop frame counter).
- Fix a lexer bug: fixed-point literals with >4 fractional digits overflowed.

Docs & tooling:
- 129 new per-symbol doc pages; gen.py made data-driven (namespaces
  discovered from the docs, no hardcoded list); new check-impl.py enforces
  that every implemented namespace method / keyword / type / phase has a
  doc page, wired into `x test-tools`. Document the previously-undocumented
  keywords (break/continue/where/entry/new/public + and/or/not tokens).
- LSP: namespaced signature help (ns_method_sig) covering every namespace.

Tests: 12 new self-host/regression tests + a golden render for the drawing
primitives. All suites green (selfhost 21, regression 45, tools 29).

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

docs/language/collide/_section.md

@@ -0,0 +1,7 @@
+---
+id: collide
+title: Collide
+order: 6
+---
+
+2D overlap tests on integer coordinates (pixels or tiles). Rectangles are <code>(x, y, w, h)</code> from the top-left; circles are <code>(x, y, r)</code>. Each returns a bool. Squared distances are computed in 64-bit so large coordinates never overflow.

docs/language/collide/collide-circles.md

@@ -0,0 +1,22 @@
+---
+id: collide-circles
+name: Collide.circles
+category: collide
+kind: namespace-method
+tokens: Collide.circles
+sig: Collide.circles(ax, ay, ar, bx, by, br) -> bool
+tip: Do two circles overlap?
+order: 2
+ns: Collide
+member: circles
+---
+
+Returns <code>true</code> when circles centred at <code>(ax, ay)</code> and <code>(bx, by)</code> with radii <code>ar</code> and <code>br</code> overlap — that is, when the distance between centres is at most <code>ar + br</code>. It compares squared distances internally, so there is no square root and no precision loss.
+
+```ludic
+program Demo {
+  handler Step phase Update {
+    if Collide.circles(px, py, 8, ex, ey, 8) { collide() }
+  }
+}
+```

docs/language/collide/collide-point_rect.md

@@ -0,0 +1,22 @@
+---
+id: collide-point_rect
+name: Collide.point_rect
+category: collide
+kind: namespace-method
+tokens: Collide.point_rect
+sig: Collide.point_rect(px, py, rx, ry, rw, rh) -> bool
+tip: Is a point inside a rectangle?
+order: 1
+ns: Collide
+member: point_rect
+---
+
+Returns <code>true</code> when the point <code>(px, py)</code> lies within the rectangle <code>(rx, ry, rw, rh)</code> — inclusive on the top-left edge, exclusive on the bottom-right. Use it for mouse or touch hit-testing against a button or a world region.
+
+```ludic
+program Demo {
+  handler Step phase Update {
+    if Collide.point_rect(mx, my, bx, by, bw, bh) { press() }
+  }
+}
+```

docs/language/collide/collide-rect_circle.md

@@ -0,0 +1,22 @@
+---
+id: collide-rect_circle
+name: Collide.rect_circle
+category: collide
+kind: namespace-method
+tokens: Collide.rect_circle
+sig: Collide.rect_circle(rx, ry, rw, rh, cx, cy, cr) -> bool
+tip: Does a rectangle overlap a circle?
+order: 3
+ns: Collide
+member: rect_circle
+---
+
+Returns <code>true</code> when the rectangle <code>(rx, ry, rw, rh)</code> overlaps the circle centred at <code>(cx, cy)</code> with radius <code>cr</code>. It finds the point on the rectangle nearest the circle's centre and checks whether it falls within the radius — the correct test for a round actor against a blocky tile.
+
+```ludic
+program Demo {
+  handler Step phase Update {
+    if Collide.rect_circle(tx, ty, 16, 16, bx, by, 6) { block() }
+  }
+}
+```

docs/language/collide/collide-rects.md

@@ -0,0 +1,22 @@
+---
+id: collide-rects
+name: Collide.rects
+category: collide
+kind: namespace-method
+tokens: Collide.rects
+sig: Collide.rects(ax, ay, aw, ah, bx, by, bw, bh) -> bool
+tip: Do two rectangles overlap?
+order: 0
+ns: Collide
+member: rects
+---
+
+Returns <code>true</code> when the axis-aligned rectangles <code>(ax, ay, aw, ah)</code> and <code>(bx, by, bw, bh)</code> overlap. Edges that merely touch do not count as overlapping. This is the standard broad-phase test for two hitboxes, tiles, or UI regions.
+
+```ludic
+program Demo {
+  handler Step phase Update {
+    if Collide.rects(px, py, 16, 16, ex, ey, 16, 16) { hit() }
+  }
+}
+```