feat(v2.2.1): release: prepare ExcelAlchemy 2.2.1

[ruicore]

Summary

This PR prepares the 2.2.1 release of ExcelAlchemy.

It continues the stable 2.x line with deeper metadata layering, stronger internal immutability, and tighter type boundaries around the Pydantic adapter layer, while keeping the public import/export workflow API stable.

What changed

Metadata layering

• make DeclaredFieldMeta, RuntimeFieldBinding, WorkbookPresentationMeta, and ImportConstraints frozen internal structures
• update FieldMetaInfo mutation paths to replace internal layer objects via structural updates instead of mutating them in place
• normalize workbook presentation internals so character sets and options are stored in immutable forms

Typing refinements

• tighten type boundaries in the Pydantic adapter around annotations, codecs, and normalized input payloads
• reduce ambiguity in metadata and adapter internals while preserving 2.x behavior

Tests and release prep

• add regression tests that verify split metadata layers behave like immutable value objects
• add regression tests that verify facade-level metadata mutation replaces internal layers rather than mutating them in place
• add 2.2.1 changelog entry
• add docs/releases/2.2.1.md

Compatibility notes

• no public import/export workflow API was removed
• FieldMeta(...) and ExcelMeta(...) remain the stable public metadata entry points
• the metadata layering changes are internal and preserve the public 2.x surface

Verification

• ./.venv/bin/ruff check .
• ./.venv/bin/uv run pyright
• ./.venv/bin/pytest -q

Release intent

After merge, this branch is intended to be tagged and published as:

• v2.2.1

[codecov]

Codecov Report

❌ Patch coverage is 92.59259% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.56%. Comparing base (dd087b6) to head (38dbbf4).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/excelalchemy/metadata.py	91.11%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #58      +/-   ##
==========================================
+ Coverage   86.48%   86.56%   +0.08%     
==========================================
  Files          48       48              
  Lines        3300     3306       +6     
  Branches      374      375       +1     
==========================================
+ Hits         2854     2862       +8     
+ Misses        278      277       -1     
+ Partials      168      167       -1     

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Reject non-codec annotations during schema extraction

_extract_pydantic_model now unconditionally falls through to yield field_adapter.runtime_metadata() for every non-composite type, so models like name: str = FieldMeta(...) are accepted instead of being rejected. That stores str as excel_codec, and later import validation calls self.excel_codec.normalize_import_value(...), which raises runtime AttributeError rather than a clear configuration ProgrammaticError at startup. This is a regression from the previous issubclass(excel_codec, ExcelFieldCodec) guard and makes invalid model declarations fail much later and less predictably.

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