go: lex.sx — operator-set audit + tilde; PHASE 1 COMPLETE + 6 tests [proposes-lex]

Adds the missing tilde operator '~' (Go 1.18+ generics type-set
constraint, e.g. 'interface { ~int | ~float64 }') to the longest-match
operator table. Adds an exhaustive 'op-audit:' test block covering
every Go operator/punctuation token by category — arithmetic +
assignment, bitwise + assignment, comparison + logical, decls /
arrows / variadic / inc-dec, punctuation, and tilde.

Phase 1 (tokenizer) is now complete. Two kit gaps surfaced and logged
in plans/go-on-sx.md Blockers for the substrate maintainer / next
statically-typed guest loop:

  * lib/guest/lex.sx lacks lex-oct-digit? / lex-bin-digit?
    (we rolled local gl-* equivalents for 0o.. and 0b.. literals).
  * lib/guest/lex.sx lacks a table-driven longest-prefix operator
    matcher; our gl-match-op is a 25-clause cond ladder. Rust/Swift/TS
    will each hit the same shape with 50+ ops apiece.

lex 129/129. Phase 2 (parser) next.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lib/go/scoreboard.md

@@ -1,10 +1,10 @@
 # Go-on-SX Scoreboard
 
-**Total: 123 / 123 tests passing**
+**Total: 129 / 129 tests passing**
 
 |  | Suite | Pass | Total |
 |---|---|---|---|
-| ✅ | lex | 123 | 123 |
+| ✅ | lex | 129 | 129 |
 | ⬜ | parse | 0 | 0 |
 | ⬜ | types | 0 | 0 |
 | ⬜ | eval | 0 | 0 |