docs: add classfile resource specification

[aofei]

Add doc/classfile-resource-spec.md to define the resource model for XGo classfile frameworks.

The specification now defines discovery-based resource introduction over project-scoped pack documents, work classfile-implied top-level resources, and static tool semantics for typed resource references.

This also updates doc/classfile-spec.md to define pack directives, pack roots, and pack documents as the standardized discovery substrate for classfile resource semantics.

Fixes #2704
Updates #2719

[gemini-code-assist]

Code Review

This pull request introduces the XGo classfile resource specification, which defines the syntax and semantics for resources in XGo frameworks, including metadata declaration, catalog document formats, and static analysis rules. The review feedback identifies an improvement opportunity in the EBNF notation section, suggesting that the ClassExt production should use a formal comment block for its description to adhere to standard conventions.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.08%. Comparing base (df19f4a) to head (f067091).

Additional details and impacted files

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  Coverage   94.08%   94.08%           
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  Files          32       32           
  Lines       10061    10061           
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  Hits         9466     9466           
  Misses        425      425           
  Partials      170      170           

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[Copilot]

Pull request overview

Adds a formal resource model spec for XGo classfile frameworks and aligns the base classfile spec terminology to support that model (including introducing the “project document” concept used for discovery).

Changes:

• Add doc/classfile-resource-spec.md defining resource kinds, canonical reference types, DQL-based discovery, scope bindings, and tool semantics.
• Clarify and tighten terminology in doc/classfile-spec.md (project/work file kinds, base class, work prototype type) and document the project document shape.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
doc/classfile-spec.md	Adds/clarifies key terms and specifies the shared JSON “project document” used by resource discovery.
doc/classfile-resource-spec.md	Introduces the full resource semantics specification for classfile frameworks (bindings, discovery, scoping, and tooling rules).

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[fennoai]

Documentation Review Summary

This is a well-structured and carefully written formal specification. The "Conformance" and "Excluded semantics" sections are clear, and the overall organization is logical. The terminology changes in classfile-spec.md are consistent and improve precision.

Below are noteworthy findings, mostly around terminology consistency and completeness within the specification.

Key themes:

• A few undefined or inconsistently-used terms that could cause ambiguity in a formal specification
• One example references an undeclared type
• The StandardDQLQuery production lacks a cross-reference to a normative DQL definition
• Minor specification-level design considerations for future implementors around resource name validation