refactor: rename 'analyzer' to 'visualize' — analysis belongs to fitter module

TODO.md

@@ -51,8 +51,8 @@ fitter/                     ← main analysis framework
 ├── result.py               ← FitResult, analysis results
 └── report.py               ← PDF report generation
 
-analyzer/                   ← visualization (stays as-is)
-└── analyzer.py             ← BetaSpectrumAnalyzer
+visualize/                  ← visualization / plotting
+└── visualize/__init__.py   ← BetaSpectrumAnalyzer
 ```
 
 ### Rationale

beta_spectrum/__init__.py

@@ -12,7 +12,7 @@ from .components.radiative import RadiativeCorrection
 from .components.detector_response import DetectorResponse
 
 from .spectrum import BetaSpectrum, SpectrumConfig, BranchConfig
-from .analyzer import BetaSpectrumAnalyzer
+from .visualize import BetaSpectrumAnalyzer
 from .fitter import CurveFitter, FitConfig, FitResult
 from .cw_extractor import CWExtractor, CWExtractionResult, GVAExtractionResult
 from .nuclear_data import (

beta_spectrum/cli.py

@@ -199,7 +199,7 @@ def _run(args: argparse.Namespace) -> None:
         BranchConfig,
         SpectrumConfig,
     )
-    from beta_spectrum.analyzer import BetaSpectrumAnalyzer
+    from beta_spectrum.visualize import BetaSpectrumAnalyzer
 
     # Determine logging level
     if args.quiet:

beta_spectrum/visualize/__init__.py

@@ -1,7 +1,7 @@
 """
-Analyzer module — BetaSpectrumAnalyzer class.
+Visualize module — BetaSpectrumAnalyzer class.
 
-Introspection, analysis, and debugging tools for BetaSpectrum.
+Visualization and plotting tools for BetaSpectrum.
 All nuclides (single- and multi-branch) are treated uniformly as one or more
 branches — single-branch is just a special case with one branch.
 """

tests/quality/test_logging_utils.py

@@ -131,7 +131,7 @@ class TestCSVMetadataHeader:
 
     def test_header_contains_version(self):
         from beta_spectrum.spectrum import BetaSpectrum, SpectrumConfig
-        from beta_spectrum.analyzer import BetaSpectrumAnalyzer
+        from beta_spectrum.visualize import BetaSpectrumAnalyzer
 
         config = SpectrumConfig(
             Z_parent=43,
@@ -159,7 +159,7 @@ class TestCSVMetadataHeader:
 
     def test_header_contains_timestamp(self):
         from beta_spectrum.spectrum import BetaSpectrum, SpectrumConfig
-        from beta_spectrum.analyzer import BetaSpectrumAnalyzer
+        from beta_spectrum.visualize import BetaSpectrumAnalyzer
 
         config = SpectrumConfig(
             Z_parent=43,
@@ -186,7 +186,7 @@ class TestCSVMetadataHeader:
 
     def test_header_contains_nuclide_info(self):
         from beta_spectrum.spectrum import BetaSpectrum, SpectrumConfig
-        from beta_spectrum.analyzer import BetaSpectrumAnalyzer
+        from beta_spectrum.visualize import BetaSpectrumAnalyzer
 
         config = SpectrumConfig(
             Z_parent=43,
@@ -214,7 +214,7 @@ class TestCSVMetadataHeader:
 
     def test_header_contains_git_commit(self):
         from beta_spectrum.spectrum import BetaSpectrum, SpectrumConfig
-        from beta_spectrum.analyzer import BetaSpectrumAnalyzer
+        from beta_spectrum.visualize import BetaSpectrumAnalyzer
 
         config = SpectrumConfig(
             Z_parent=43,
@@ -241,7 +241,7 @@ class TestCSVMetadataHeader:
 
     def test_header_contains_corrections(self):
         from beta_spectrum.spectrum import BetaSpectrum, SpectrumConfig
-        from beta_spectrum.analyzer import BetaSpectrumAnalyzer
+        from beta_spectrum.visualize import BetaSpectrumAnalyzer
 
         config = SpectrumConfig(
             Z_parent=43,