passes: implement control-flow pass (4 schemes + rotation)

FlowPass rebuilds one method per scheme picked from FlowConfig:
state-spread (dense tableswitch dispatcher), computed-switch
(sparse lookupswitch over a counter local), butterfly (branch
inversion), exception-goto (dispatcher under try with a dead
catch-all), plus opaque goto-splices inside every method and
StackMapTable recomputation afterwards. Now in standard_pipeline
(between constants and noise); --no-flow is an honest off-flag.

Acceptance is real JVM, not shapes: per-scheme verify, rotation
spread, calc-prints-45 execution, paranoid smoke on lorep-1.1.0
(131 methods rebuilt, no new failures over standard).

Two verifier rules learned the hard way are now construction
invariants: no inserted mark shares a bytecode offset with a
foreign one (nop pads), and no frameless gap follows a terminal
(dead blocks are opaque-entered and throw).

Also fixes a latent frame-emitter bug the pass exposed: wide
stack values were written as slot pairs ([Double, Top]) while
javac writes one entry ([Double]); HotSpot rejects the pair.
Stacks now collapse like locals (emit::stack_vars), with a
regression test in classfile/tests/frames.rs.

docs/learnings/reference.md

@@ -26,7 +26,7 @@
 | `StringDecoderGenerator` | 205 | генерит класс-декодер | `noxis-runtime` + P2 генератор |
 | `ObfuscatorRunner` | 202 | конвейер, оркестрация | `noxis-passes::standard_pipeline` ✅ |
 | `NumberObfuscator` | 185 | константы / opaque | пасс `constants` |
-| `ControlFlowObfuscator` | 183 | flattening | пасс `flow` (ждёт `StackMapTable`) |
+| `ControlFlowObfuscator` | 183 | flattening | пасс `flow` ✅ (4 схемы, свои кадры) |
 | `FabricKeepRuleScanner` | 147 | keep из конфига Fabric | `noxis-analysis::keep` ✅ |
 | `Main` | 134 | CLI-точки | `noxis` (clap) |
 | `StringEncryptor` | 132 | AES-128 строк + chunk'и | `noxis-runtime::scheme` ✅ |