chore: Update methodology for Linear TV and Classic OOH (GMSF v1.3)

[pymble2073]

Re-applies the GMSF v1.3 methodology changes from PR #289, which were reverted in PR #290 due to a production incident (Methodology defaults file version 24 is not supported). The API has since been updated to support the new defaults count.

Reverts PR #290 (revert: revert-pr289-channel-methodology).

Changes

• Linear TV: Adds transcoding/datacenter compute defaults for future API use; updates signal preparation and transmission power/embodied values to GMSF v1.3
• Classic OOH: Adds physical production defaults (materials, mass, substrate production, manufacturing, EOL, transport distances, illumination)
• Physical production: New defaults_physical_production.mdx with default_production_loss_ratio_by_channel (classic-ooh and print: 1.11, all others: 1)
• Docs: Updates channel_considerations.mdx and calculations.mdx for GMSF v1.3 guidance; replaces all GMSF 1.2 PDF links with canonical URL
• Fix: yaml_dump now uses CustomDumper to preserve correct list indentation in docs-defaults.yaml

Closes https://linear.app/scope3-projects/issue/SUS-97/update-methodology-repo-for-linear-tv-and-classic-ooh

Test plan

• CI passes
• API updated to handle 128 defaults before merging

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