Lint: Register ++/-- increment/decrement in UnsupportedRegistry

[PurHur]

Problem

Loop counters and pagination use ++$i / $i++ (#137). Until implemented, phpc lint should point to #137 instead of a generic Unsupported expression for PreInc, PostInc, PreDec, PostDec.

Goal

Map php-cfg increment/decrement expression kinds in UnsupportedRegistry + docs/unsupported-syntax.md.

Scope

• Confirm kind strings (Expr_PreInc, etc.) via lint probe
• Registry entries → Language: Pre/post increment and decrement (++/--) #137
• UnsupportedRegistryTest + docs row
• Implementation remains Language: Pre/post increment and decrement (++/--) #137

Acceptance criteria

./phpc lint -r '++$i;' 2>&1 | grep 137

Verification

docker run --rm -v "$(pwd):/compiler" -w /compiler php-compiler:22.04-dev \
  vendor/bin/phpunit --filter UnsupportedRegistryTest

Links

• Language: Pre/post increment and decrement (++/--) #137, Language: while, do-while, and for loops (CFG → VM → JIT) #192 loops, 🗺️ ROADMAP: Compile a small PHP web application (living document) #78 Phase 2