feat: add HWPX fragment paste support

[dragonnite1221-lgtm]

Adds HWPX fragment paste support, WASM bridge APIs, rhwp-studio insertion UI, and regression tests. Internal work logs, local environment paths, and operational notes were intentionally excluded from this public branch.

Architecture note: this PR intentionally keeps two paste entry points for different safety boundaries.

• pasteHwpxFragment / fragment_paste.rs is the raw XML primitive. It performs byte-preserving section/header edits and owns HWPX ID remapping for raw snippets.
• pasteHwpxFragmentInDocument / fragment_paste_in_document.rs is the editor-facing bridge. It reuses the raw XML primitive, then reparses the updated section back into DocumentCore so rendering and later edit commands stay in sync.
• cross_document_migrate.rs is the IR migration primitive for future structured cross-document copy/paste. It is kept separate from the raw HWPX fragment path because it operates on Document/DocInfo IR, not byte-preserved HWPX XML. The convergence point is at the command/API layer: raw HWPX fragments use the byte-preserving path now; structured IR copy/paste can use the migration primitive once the editor exposes that workflow.

Review follow-up in this revision:

• Rebased onto current origin/devel and preserved the HWPX external-image path fix in parse_hwpx_with_raw_xmls.
• Removed the as any call by using the generated WASM binding type for pasteHwpxFragmentInDocument.
• Removed local-machine yangsik smoke tests and made the remaining Document bridge tests use the bundled saved/04-blank_hwpx_empty.hwpx fixture so CI gets real regression coverage.
• Aligned the blank HWPX seed comment with saved/04-blank_hwpx_empty.hwpx.
• Removed the unused build_occupied_sets helper.

Validation performed locally:

• cargo test --test fragment_paste_integration --test fragment_paste_in_document
• cargo test fragment_paste
• npm run build in rhwp-studio/

[dragonnite1221-lgtm]

Updated the branch on top of current origin/devel and resolved conflicts in rhwp-studio/index.html, rhwp-studio/vite.config.ts, and src/document_core/mod.rs.

Current validation after rebase:

• gitleaks detect --source . --log-opts origin/devel..HEAD --redact --no-banner --verbose: no leaks found
• sensitive string scan on origin/devel..HEAD: no internal paths/IP/token patterns found
• cargo test fragment_paste --tests: passed
• docker compose --env-file .env.docker run --rm wasm: passed, local pkg regenerated for verification
• cd rhwp-studio && npm run build: passed

I also added a local pre-push guard in my working copy to prevent accidentally pushing local/*, archive/internal/*, or public branches containing internal paths such as mydocs/.

[edwardkim]

Welcome to the rhwp project, @dragonnite1221-lgtm! 🎉 This is your first PR and the scope is impressive — HWPX fragment paste with both raw XML and IR migration paths, a yangsik dialog, and thorough test coverage.

We've completed a detailed code review. The overall quality is good, but there are a few items to address before we can merge.

What we liked

• Dual approach (raw XML path + IR migration path) with independent tests for each
• Byte-preserving principle consistently applied
• Path traversal defense in vite-plugin-yangsik-fragments.ts
• ~40 unit tests + 4 integration tests — solid coverage

Requested changes

1. Dual implementation overlap (medium)

fragment_paste.rs (raw XML ID remap) and cross_document_migrate.rs (IR ID remap) implement the same purpose with separate IdRemap structs. The WASM bridge exposes two entry points (pasteHwpxFragment + pasteHwpxFragmentInDocument) but the PR description doesn't explain why both are needed or how they'll converge.

Ask: Please add a note in the PR description explaining the intent, or consolidate into one path if the other is experimental.

2. Type cast in wasm-bridge.ts (medium)

(this.doc as any).pasteHwpxFragmentInDocument(...)

This bypasses compile-time type safety. Please add the method to the WASM binding type definition instead of using as any.

3. Environment-dependent tests (medium)

fragment_paste_in_document_yangsik.rs depends on ~/rhwp-layout-profiles/personal-templates/양식_3bf55ee3.hwpx — a path that only exists on your local machine. These tests are always skipped in CI and provide no regression protection.

Ask: Either bundle a small test fixture in saved/ or samples/, or remove the environment-dependent tests and keep only the self-contained ones.

4. Comment/code mismatch (low)

wasm_api.rs comments reference saved/03-blank_hwpx.hwpx but the actual added file is saved/04-blank_hwpx_empty.hwpx. Please align the comment.

5. Unused function (low)

build_occupied_sets in fragment_paste.rs appears to be defined but the same logic is reimplemented inline in recompute_one_table. This may trigger dead_code warnings. Please remove the unused function or use it.

How to proceed

1. Address items baseline/line_height/line_spacing 역공학 #1–cellzoneList(셀 영역 배경) 미지원으로 표 배경 누락 #5 above
2. Rebase onto current devel to resolve the conflict
3. Push the updated branch — we'll re-review

We're also happy to discuss architecture decisions (e.g., the dual-path approach) in a GitHub Discussion or Issue if that would help.

Thank you for the contribution, and looking forward to the updated PR!