ludicc --emit-syntax: the language's vocabulary as one table beside the parser

selfhost/frontend/vocab.ludic holds every keyword with its role (declaration,
modifier, statement, operator, constant), every declaration's form, the built-in
types and phases, every attribute with what it goes on, its arguments and a
one-line doc, the operators and the literal forms; `ludicc --emit-syntax` prints
it as JSON ("syntax_version": 1) and exits before reading any program. The
parser dispatches on words where it meets them, so the table is held to it from
the emitter's side: a keyword's "reserved" is is_reserved_word's answer, a phase
must pass is_phase_name and a field attribute listed as read must pass
at_field_known, or the emitter refuses to print. Reseeded (both seeds assemble;
bootstrap-cfree: out.ll == seed.ll).

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

selfhost/main.ludic

@@ -162,6 +162,7 @@ entry {
     else if a == "--release" { g_release = true }        # what ships: Build.schema_hash() is 0 (emit_schema_hash.ludic)
     else if a == "--diagnostics=json" { g_diag_json = true }     # every error, as JSON on stdout (diag.ludic)
     else if a == "--diagnostics=text" { g_diag_json = false }
+    else if a == "--emit-syntax" { syntax_emit() }        # the language's vocabulary as JSON (frontend/vocab.ludic)
     else if a == "--emit-schema" { ai += 1;  if ai < arg_count() { g_schema_out = arg(ai) } }   # emit_schema.ludic
     else if a == "--globals" { g_allow_globals = true }
     else if a == "--migrate-state" {                     # 0.S2: write the plan ludic migrate state applies