feat(lang): a component's event may be called set, a string prop reads a number, one name per component

- An action whose first word is `set` or `emit` followed by `(` is a call, so a component's
  `on set(v: int)` is pressed as `set(4)`; `set x = ...` is still the action.
- A `string` prop (or state, or parameter) given a number in a template reads it as text through
  ludic.ui's new `ui_val_text`; `label="{3}"` used to arrive as "".
- Two components of one name (or of names that differ only in case, which share their functions'
  names) are an error at the second declaration that names the first's file and line, instead of a
  "function cmp_x_def_y is defined twice".

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

packages/ludic.ui/act.ludic

@@ -1,5 +1,6 @@
 # act.ludic - what a press does: `buy(i)` asks the view, `set pick = i` changes a state, and
-# `emit picked` runs what the component's user said with on-picked. Several are `;` apart.
+# `emit picked` runs what the component's user said with on-picked. Several are `;` apart. A call
+# of a function named set or emit (`set(4)`, a component's `on set(v)`) is a call.
 const A_CALL: int = 0
 const A_SET: int = 1
 const A_EMIT: int = 2
@@ -18,12 +19,12 @@ function act_parse(src: string, err: []string) -> UiAct {
   while r.err == "" {
     rd_ws(r)
     if r.i >= len(r.s) { break }
-    if rd_word(r, "set") {
+    if act_keyword(r, "set") {
       push(a.kinds, A_SET)
       push(a.names, rd_name(r))
       if not rd_op(r, "=") { rd_fail(r, "'='") }
       push(a.exprs, px_cond(r))
-    } else if rd_word(r, "emit") {
+    } else if act_keyword(r, "emit") {
       push(a.kinds, A_EMIT)
       push(a.names, rd_name(r))
       push(a.exprs, null)
@@ -39,6 +40,17 @@ function act_parse(src: string, err: []string) -> UiAct {
   if r.err != "" { push(err, r.err) }
   return a
 }
+# `set` or `emit` as the action's first word - not a function of that name, as in `set(4)`
+function act_keyword(r: UiRd, word: string) -> bool {
+  let at = r.i
+  if not rd_word(r, word) { return false }
+  rd_ws(r)
+  if r.i < len(r.s) and r.s[r.i] == 40 {
+    r.i = at
+    return false
+  }
+  return true
+}
 function act_run(a: UiAct, e: UiEnv) -> void {
   for i in 0 .. len(a.kinds) {
     if a.kinds[i] == A_SET { env_set(e, a.names[i], ui_eval(a.exprs[i], e)) }