feat(canonicalizer): Phase 143-P0 - parse_number pattern support

Add parse_number pattern recognition to canonicalizer, expanding adaptation
range for digit collection loops with break in THEN clause.

## Changes

### New Recognizer (ast_feature_extractor.rs)
- `detect_parse_number_pattern()`: Detects `if invalid { break }` pattern
- `ParseNumberInfo`: Struct for extracted pattern info
- ~150 lines added

### Canonicalizer Integration (canonicalizer.rs)
- Parse_number pattern detection before skip_whitespace
- LoopSkeleton construction with 4 steps (Header + Body x2 + Update)
- Routes to Pattern2Break (has_break=true)
- ~60 lines modified

### Export Chain (6 files)
- patterns/mod.rs → joinir/mod.rs → control_flow/mod.rs
- builder.rs → mir/mod.rs
- 8 lines total

### Tests
- `test_parse_number_pattern_recognized()`: Unit test for recognition
- Strict parity verification: GREEN (canonical and router agree)
- ~130 lines added

## Pattern Comparison

| Aspect | Skip Whitespace | Parse Number |
|--------|----------------|--------------|
| Break location | ELSE clause | THEN clause |
| Pattern | `if cond { update } else { break }` | `if invalid { break } rest... update` |
| Body after if | None | Required (result append) |

## Results

- ✅ Skeleton creation successful
- ✅ RoutingDecision matches router (Pattern2Break)
- ✅ Strict parity OK (canonicalizer ↔ router agreement)
- ✅ Unit test PASS
- ✅ Manual test: test_pattern2_parse_number.hako executes correctly

## Statistics

- New patterns: 1 (parse_number)
- Total patterns: 3 (skip_whitespace, parse_number, continue)
- Lines added: ~280
- Files modified: 8
- Parity status: Green ✅

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/mir/builder.rs

@@ -33,6 +33,10 @@ mod control_flow; // thin wrappers to centralize control-flow entrypoints
 
 // Phase 140-P4-A: Re-export for loop_canonicalizer SSOT (crate-wide visibility)
 pub(crate) use control_flow::{detect_skip_whitespace_pattern, SkipWhitespaceInfo};
+// Phase 142-P1: Re-export continue pattern detection for loop_canonicalizer
+pub(crate) use control_flow::{detect_continue_pattern, ContinuePatternInfo};
+// Phase 143-P0: Re-export parse_number pattern detection for loop_canonicalizer
+pub(crate) use control_flow::{detect_parse_number_pattern, ParseNumberInfo};
 mod exprs_lambda; // lambda lowering
 mod exprs_peek; // peek expression
 mod exprs_qmark; // ?-propagate