Add template doctor workflow to analyze and repair real-world PowerPoint templates

[jongalloway]

Summary

Add a template doctor workflow that goes beyond template diagnostics and helps normalize or repair real-world PowerPoint templates so they work better with MarpToPptx.

This should complement, not replace, #85:

• template diagnose answers "what is in this template and which layouts should I use?"
• template doctor answers "what is structurally wrong or unhelpful for MarpToPptx, and can we fix or normalize it?"

Motivation

Real-world conference and corporate templates are often valid PowerPoint files but still produce poor results with MarpToPptx:

• layout names are inconsistent or duplicated
• title/body placeholder identity exists, but usable geometry is inherited only from master shapes
• placeholder wiring is inconsistent across related layouts
• layouts have picture/content slots that are not easy to target semantically
• templates may technically open fine in PowerPoint while still leading to overlapping content, weak layout differentiation, or hard-to-predict results in generated decks

Recent investigation against a real conference template showed exactly this class of problem: the content layout exposed title and body placeholder identities, but the usable body geometry lived on the slide master rather than the layout itself. That is recoverable for rendering, but it is also a strong signal that a template-oriented fixer / normalizer could improve authoring predictability and renderer interoperability.

Proposed Scope

Add a workflow that can inspect a .pptx template and produce:

• structural warnings about layout/master relationships that are likely to degrade MarpToPptx output
• recommended normalizations that would make the template easier to consume semantically
• optionally, a repaired or normalized template output for safe, common fixups

Candidate checks:

• duplicate or missing layout names
• title/body placeholders missing on targeted content layouts
• usable placeholder geometry present only via master inheritance
• inconsistent placeholder type / idx wiring between similar layouts
• likely content layouts that only expose typeless indexed placeholders
• picture placeholders and multi-content layouts that cannot yet be mapped well
• layouts that are visually redundant from a MarpToPptx perspective

Candidate safe fixups:

• normalize or suggest layout names
• materialize inherited placeholder geometry onto layouts when appropriate
• standardize placeholder metadata for title/content layouts
• emit a repaired copy of the template with a report of what changed

Suggested UX

Possible forms:

• CLI command such as marp2pptx template doctor --template conference.pptx
• --json output plus human-readable console summary
• dry-run mode that reports proposed fixups without writing a new file
• explicit --write-fixed-template or similar flag for safe write-back into a new output file

Acceptance Criteria

• Given a .pptx template, the workflow reports template problems that are specifically relevant to MarpToPptx rendering.
• The report distinguishes between informational diagnostics, warnings, and fixable issues.
• The workflow can identify at least a first set of safe, automatable repairs.
• Dry-run mode clearly reports what would change.
• If write mode is supported, the tool writes a new normalized template rather than mutating the original in place.
• The behavior is documented alongside existing template guidance.

Relationship To Existing Work

• #85 tracks template diagnostics and recommended layout guidance.
• This issue tracks the next step: template normalization / repair for templates that are technically valid but poorly shaped for MarpToPptx.

Notes

This would be especially useful when onboarding conference or corporate templates that were authored for manual PowerPoint use rather than semantic generation pipelines.