feat(ux): storage namespacing pragma

[fubuloubu]

What I did

Implement the #pragma storage-namespace directive that allows contracts to declare a global storage namespace, shifting the base storage slot from 0 to a calculated offset based on ERC-7201.

Key changes:

• Add storage_namespace field to Settings dataclass
• Parse storage-namespace pragma in pre_parser.py
• Implement erc7201_storage_slot() function in utils.py that calculates the namespace slot using the ERC-7201 formula: keccak256(keccak256(id) - 1) & ~0xff
• Modify Allocators to accept a starting slot for storage allocation
• Update storage layout export to include namespace information
• Add comprehensive tests for the new functionality

The pragma accepts either:

• A namespace string (e.g., #pragma storage-namespace myapp.storage.v1) which is hashed using ERC-7201
• A hex value (e.g., #pragma storage-namespace 0x1000) which is used as a raw slot value

This feature enables modular contract architectures like Diamond Standard and supports ERC-7201 namespaced storage patterns.

fixes: #4647

How I did it

100% Claude Code

How to verify it

• Verify storage slot output using namespaces
• Verify no conflicts when used with Purse

Commit message

feat: add storage-namespace pragma directive

Allows contracts to declare a global storage namespace, shifting the base storage slot from 0 to a calculated offset based on ERC-7201

Description for the changelog

add storage-namespace pragma directive

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.30%. Comparing base (9964d42) to head (0523d56).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4810      +/-   ##
==========================================
+ Coverage   93.29%   93.30%   +0.01%     
==========================================
  Files         148      148              
  Lines       20592    20628      +36     
  Branches     3577     3585       +8     
==========================================
+ Hits        19211    19247      +36     
  Misses        924      924              
  Partials      457      457              

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[fubuloubu]

Simpler

[fubuloubu]

Suggested change

	if pragma.startswith("storage-namespace") and (
	pragma == "storage-namespace" or pragma.startswith("storage-namespace ")
	):
	if pragma.startswith("storage-namespace"):

[fubuloubu]

Question: do we want this pragma to impact transient storage as well? Or require a separate pragma?

[fubuloubu]

Was thinking to rename this to:

Suggested change

	def __init__(self, storage_starting_slot: int = 0):
	def __init__(self, starting_slot: int = 0):

[fubuloubu]

Streamline this test