Docs: standardize Densetsu engine page scaffolds and add tooling/utility pages

[Kaizersensei]

Motivation

• Reduce inconsistent stubs and make engine docs scannable by introducing a consistent scaffold and explicit section guidance for each engine page.
• Surface operational and authoring guidance from local project notes into documented pages so editors and engineers have a predictable landing zone.
• Capture several project-owned editor tools and utilities in the docs so tool inventory and ownership are discoverable.

Description

• Replaced one-off TODO stubs across many engine pages (for example engine/index.html, actors/*, fsm/*, runtime/*, input_movement/*, rendering/*, stats_combat/*, data_authoring/*) with a uniform scaffold that includes a Content status callout and standard sections: At a glance, How it works, Interfaces, Operational concerns, Related docs, and raw details blocks.
• Removed large autofill/missing-info blocks and consolidated guidance into the new concise template and updated the template file meta/TEMPLATE_ENGINE_PAGE.html.
• Added multiple new tooling and debug pages under pages/docs/projects/densetsu/engine/tools/ including autocliff_terrain3d_overview.html, autocliff_dock_usage_and_troubleshooting.html, debug_tools_overview.html updates, foliage_system_overview.html, geometry_obj_export_overview.html, hitbox_hurtbox_bridge_overview.html, project_audit_overview.html, texture_maps_overview.html, tool_suite_overview.html, and vertex_edit_overview.html to document editor plugins and workflows.
• Minor content imports: copied selected raw excerpts and local notes into collapsed details blocks for traceability on several pages.

Testing

• No automated tests were run as part of this change.
• This PR contains only static documentation HTML changes and new pages; recommend validating with the site generation/publishing pipeline and a local site build before merging.

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Codex Task

[Kaizersensei]

Applied the tooling-doc portion of this PR directly onto main because the PR no longer merges cleanly after subsequent main changes. Landed on main: engine/index.html, tools/debug_tools_overview.html, and the new tooling pages for Autocliff, Foliage, Geometry OBJ Export, Hitbox Hurtbox Bridge, Project Audit, Texture Maps, Tool Suite, and Vertex Edit. The broader engine-page scaffold refactor in this PR is still pending manual conflict resolution if we want to bring over the remaining non-tooling docs changes.

[Kaizersensei]

Second manual backport pass is now on main as well. I applied the remaining PR #4 scaffold/template pages directly onto main so GitHub Pages can use that structure as the baseline even though the PR still conflicts.

This includes the remaining runtime pages, stats/combat pages, telemetry/index.html, testing-qa/index.html, and pages/docs/projects/densetsu/meta/TEMPLATE_ENGINE_PAGE.html.

The PR can stay open for recordkeeping or be closed later if we decide the direct-to-main baseline is the canonical path forward.