fix(lang-v2): preserve qself in InitSpace type paths

[0x4ka5h]

Findings (AI # 69 & # 68):

InitSpace mishandles type paths: it drops qself on qualified associated types, and matches built-in sizes by final segment only, so custom::Address gets 32 bytes .

Fix:

Quote the full TypePath in the fallback, and apply built-in shortcuts only to unqualified single-segment paths so qualified types use <Type as Space>::INIT_SPACE.

[hacktron-app]

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[codecov-commenter]

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Codecov Report

❌ Patch coverage is 93.47826% with 3 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (anchor-next@e4878b6). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
lang-v2/derive/src/init_space.rs	93.47%	3 Missing ⚠️
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Additional details and impacted files

@@              Coverage Diff               @@
##             anchor-next    #4901   +/-   ##
==============================================
  Coverage               ?   64.65%           
==============================================
  Files                  ?      127           
  Lines                  ?    16621           
  Branches               ?        0           
==============================================
  Hits                   ?    10746           
  Misses                 ?     5875           
  Partials               ?        0           

Flag	Coverage Δ
v2	64.65% <93.47%> (?)

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