feat(compiler): list literals, typed compound assignment, file:line diagnostics

- `[a, b, c]` list literals (E_LIST → emit_list); static_type learns
  slice-element, `new T`, list, string and literal kinds
- `x op= y` lowers through the same path as `x = x op y` (emit_bin_vals):
  fixed `*=`/`/=` use the Q16.16 64-bit paths, string `+=` concatenates,
  int→long widens; unary `-` keeps a fixed operand's type (arith_ty)
- one `unescape()` table for "strings", 'chars' and `interpolation`;
  `'\''`, `'\\'`, `'\"'` no longer read as 0; unterminated char literals
  and unexpected characters are errors instead of silently skipped
- every diagnostic is `file:line: error: msg` (g_parse_file / g_err_file,
  Node.file + Node.line set by node()); tok_desc() in expectation errors;
  duplicate `function` names and unknown `phase` names are reported in
  source terms (phase_id used to default unknown phases to Overlay)
- interpolation holes skip braces inside string literals
- hand-IR preludes move from the user `@fn_` prefix to `@lp_` so a user
  `is_ws` / `str_eq` / `path_join` no longer collides at link time
- `@ClearColor(expr)` accepts any constant expression; `Os.pid()` added
  (docs page + inventory); `str_starts()` in support/str
- main.ludic: `else if` flag ladder, char literals, stale script comments
- examples/lang/operators.ludic covers all of the above; os.ludic covers
  Os.pid; docs pages for Os.pid and the Overlay phase; ten changesets
- reseeded: selfhost/ludicc.seed.ll is the new compiler's own fixpoint

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/language/annotations/annot-clearcolor.md

@@ -9,7 +9,7 @@ tip: Declare a clear colour so the Render phase auto-clears + auto-presents for
 order: 62
 ---
 
-<code>@ClearColor(N)</code> declares the framebuffer clear colour (a <code>0x00RRGGBB</code> integer) so the engine owns the per-frame clear and present: at the top of the Render phase it clears the framebuffer to <code>N</code>, and after all Render handlers run it presents the frame — so a game's Render handler carries no <code>Screen.clear</code> / <code>Screen.show</code> boilerplate, and the colour is configured declaratively rather than written in the handler body. It is opt-in: a program with no <code>@ClearColor</code> is byte-for-byte identical (it clears and presents itself, or the light system owns the present). Place it on the program's Render handler (or any declaration — it is program-wide).
+<code>@ClearColor(N)</code> declares the framebuffer clear colour (a <code>0x00RRGGBB</code> integer) so the engine owns the per-frame clear and present: at the top of the Render phase it clears the framebuffer to <code>N</code>, and after all Render handlers run it presents the frame — so a game's Render handler carries no <code>Screen.clear</code> / <code>Screen.show</code> boilerplate, and the colour is configured declaratively rather than written in the handler body. It is opt-in: a program with no <code>@ClearColor</code> is byte-for-byte identical (it clears and presents itself, or the light system owns the present). Place it on the program's Render handler (or any declaration — it is program-wide). The argument is any constant expression — a hex literal, a `Color.*` name, or a `const` from your palette.
 
 ```ludic
 program ClearColorDemo {

docs/language/annotations/annot-ondespawn.md

@@ -19,7 +19,7 @@ program DespawnHook {
 
   @OnDespawn(Enemy, reason: teardown_reason) handler DropLoot {
     match teardown_reason {
-      EndReason.Quit => {}                            # app closing — do not drop loot
+      EndReason.Quit => { }                            # app closing — do not drop loot
       _              => { print(Loot.gold) }          # died in-world — award the gold
     }
   }

docs/language/annotations/annot-sync.md

@@ -14,7 +14,7 @@ These are the two declarative switches at the top of Ludic's networking: <code>@
 ```ludic
 program SyncedWorld {
   @Sync property Position { column: int = 0, row: int = 0 }   # every field replicable
-  property Health { @Sync current: int = 0, maximum: int = 0 } # only current replicable
+  property Health { @Sync current: int = 0, maximum: int = 0 }  # only current replicable
 
   @Owned model Player { @Sync Position, @Sync Health }         # participates -> column,row,current
   model Scenery { Position }                                   # not @Sync here -> never replicates