chore: update all module READMEs to use main agent id

[phorcys420]

Summary

This PR standardizes all module documentation examples to use coder_agent.main instead of coder_agent.example, aligning with the most common template convention.

Problem

Currently, there's an inconsistency between template definitions and module documentation:

• Templates: 78% (21 of 27) use "main" as the agent name
• Module documentation: Most of examples use "example" as a placeholder, which doesn't exist in any templates, except some modules who already use "main"

This creates friction when users copy examples from module docs into their templates that use main as the agent name.

Solution

Update all module documentation to use coder_agent.main since:

1. It matches the most common convention (21 of 27 existing templates)
2. Creates consistency between docs and real-world usage
3. Reduces the need for users to edit copy-pasted examples

Changes

Module Documentation (52 files)

• ✅ Updated 50+ module README.md files from coder_agent.example → coder_agent.main
• ✅ Updated root README.md
• ✅ Updated CONTRIBUTING.md
• ✅ Updated examples/templates/main.tf

What's NOT in this PR

❌ Template changes - Templates are left as-is to avoid breaking existing workspaces
❌ Linting rules - Will be addressed separately if desired

Impact

✅ Zero breaking changes: Only documentation is updated
✅ Better DX: Copy-paste examples work with 78% of existing templates
✅ Consistency: Documentation now matches the de facto standard

Testing

• ✅ All changes verified with git diff
• ✅ Only modified documentation files (52 files changed)
• ✅ 200 insertions, 200 deletions (pure substitution)

Related

This addresses the documentation inconsistency identified in the registry audit. Template standardization can be addressed in a future PR if desired.

PR by @phorcys420
Non-blink follow-up to #566

[phorcys420]

just did find&replace of coder_agent\.(.*)\.id to coder_agent.main.id, all changes seem to be correct, and untouched modules already were using coder_agent.main.id or didn't need an agent

[matifali]

Thanks @phorcys420, a good follow-up would be to update all example templates to use main as the name for the coder_agent resource.

[phorcys420]

@matifali yes that is planned too, just didn't do it yet as it needed more testing