Sync API docs from bc3

[jorgemanrubia]

This is a full sync of bc3's doc/api/ at master 821ea0352f. The person-types change prompted it, but the copy also brings over every earlier bc3 doc change that had not yet been mirrored here. Each one is listed below with the bc3 PR it came from, so its owner can review their part.

What this carries

• Person types (bc3#13381, the reason for this sync)
  • A new "Person types" section in README.md: which person objects include personable_type, what each current type means, and that new types may appear, so clients should handle an unknown value gracefully.
  • A note in sections/people.md that points to that section.
• Account event feed
  • New sections/event_feed.md, plus its entry in the README.md index.
  • From bc3#13049, #13053, #13054, #13056, #13058, #13339, #13362, #13364 and #13365.
• Card table and to-do list templates (bc3#13312)
  • New sections/card_table_templates.md and sections/templatifications.md, plus their README.md index entries.
  • Changes to sections/projects.md and sections/template_library.md, including copying a template by naming its destination project.
• Authorization document (bc3#13317): sections/authentication.md.
• Over-long boosts (bc3#13357): sections/boosts.md, which now documents a 422.
• Agents in the timeline (bc3#12314): sections/timeline.md.
• Changing your email address (bc3#13217): sections/people.md now says it needs an identity-wide token.

No files are removed.

Overlap with #437

#437 (join a project) edits sections/people.md, and so does this PR.

• Document joining an all-access project (POST /buckets/:id/admissions.json) #437 already conflicts with master on that file, so this PR doesn't create the conflict.
• This PR doesn't include Document joining an all-access project (POST /buckets/:id/admissions.json) #437's content: bc3's doc/api has no admissions section.
• Document joining an all-access project (POST /buckets/:id/admissions.json) #437 is untouched.

Synced from bc3 doc/api/ by script/api/sync_to_bc3_api — not a hand-edit.

[Copilot]

🟡 Changes recommended

Several examples have mismatched resource IDs or missing required markers, and timeline attribution omits valid tombstoned performers.

Get a fresh assessment by requesting another Copilot review.

Pull request overview

Syncs accumulated API documentation from bc3, covering person types, event feeds, templates, authorization, and related examples.

Changes:

• Documents person types and delegated agent attribution.
• Adds event-feed, card-table-template, and templatification APIs.
• Refreshes authorization, project, boost, and template-library documentation.

[!TIP]
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File summaries

File	Description
README.md	Adds person types and endpoint index entries.
sections/authentication.md	Updates Basecamp authorization documents.
sections/boosts.md	Documents boost length validation.
sections/card_table_templates.md	Adds card-table template APIs.
sections/event_feed.md	Adds account event-feed documentation.
sections/people.md	Documents person types and email-token requirements.
sections/projects.md	Refreshes project response examples.
sections/template_library.md	Expands to-do template and copy APIs.
sections/templatifications.md	Adds asynchronous templatification APIs.
sections/timeline.md	Documents delegated event performers.

Review details

Suppressed comments (3)

sections/event_feed.md:445

• This response example lacks the matching route comments required by AGENTS.md:43. Wrap it with <!-- START GET /inbox.json --> and <!-- END GET /inbox.json --> so it participates in the repository's standard example-maintenance flow.

###### Example JSON Response

sections/card_table_templates.md:521

• The completed copy has id: 1 and a /copies/1.json URL, but these START/END markers label it as copy 2. Change both markers to /copies/1.json and add the required ###### Example JSON Response heading (AGENTS.md:43) so extraction and rendered documentation identify this example correctly.

<!-- START GET /template_library/copies/2.json (card table) -->

sections/event_feed.md:510

• This response example lacks the matching route comments required by AGENTS.md:43. Wrap the JSON block with <!-- START POST /events/stream_ticket.json --> and <!-- END POST /events/stream_ticket.json --> to keep the new endpoint consistent with the documented section format.

###### Example JSON Response

• Files reviewed: 10/10 changed files
• Comments generated: 4
• Review effort level: Balanced

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[jorgemanrubia]

🤖 Copilot's four findings are real. They're in docs carried over from bc3, not in the person-types change. This repo only mirrors bc3's doc/api/, so the fixes go into bc3 as their own PR, and then this branch gets re-synced. I'll reply on each thread and resolve it once the re-sync is pushed.