fix: upload large images/resize images in headers/footers

[VladaHarbour]

No description provided.

[linear-code]

SD-3067

[github-actions]

Status: PASS

The two changed files only deal with the image relationship plumbing for header/footer parts. I verified the OOXML constructs they touch:

• The new IMAGE_REL_TYPE = 'http://schemas.openxmlformats.org/officeDocument/2006/relationships/image' constant matches the canonical OPC relationship type for image parts (ECMA-376 Part 1 §15.2.x), and it's just hoisted from the inline literal already used in addImageRelationshipForId. No semantic change to the emitted <Relationship> element.
• The <Relationship> element written by addImageRelationshipForId keeps the same required attributes (Id, Type, Target) — no TargetMode (correct, since image parts are internal).
• The header/footer reuse path in translateImageNode only reads params.existingRelationships and copies rel.attributes.Id into a:blip/@r:embed. That's the spec-correct way to reference an internal image part from DrawingML (§20.1.8.13 a:blip).
• The test's fixture relationship (Id: rIdHeaderImage, Type: …/relationships/image, Target: media/test.png) is a valid header-part-local rel: the target is resolved relative to word/_rels/header1.xml.rels, which is consistent with how the rest of the PR writes header/footer rels.

No non-existent attributes, no missing required ones, and the default-value semantics are unchanged from the prior code path. See https://ooxml.dev/spec?q=blip and https://ooxml.dev/spec?q=Relationship if you want to cross-reference.

[chatgpt-codex-connector]

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