[ADD] attachment_preview_office: preview Office attachments via Libre…

[alan196]

…Office

Convert DOCX/XLSX/PPTX (and legacy/ODF) attachments to PDF server-side with LibreOffice headless and render them with Odoo's native PDF.js viewer, including chatter attachments. No external viewer service is involved, so documents never leave the server. Converted PDFs are cached on disk keyed by content checksum.

Conversion endpoint logic based on OCA#603 (18.0).

[jarsabot]

    **WARNING**: Could not link to Odoo task. Record ID not found in the title of the MR, supported formats:

{ record type }#{ number }

Available types: 'task#', 't#' (case insensitive)

Examples:

• task#123

• i#123

[jarsabot]

    **WARNING**: Could not link to Odoo task. Record ID not found in the title of the MR, supported formats:

{ record type }#{ number }

Available types: 'task#', 't#' (case insensitive)

Examples:

• task#123

• i#123

[codecov-commenter]

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