docs: add project support and triage hygiene policy

[bmdavis419]

Summary

• add public support/triage policy document
• improve issue templates for reproducibility and routing
• link support policy from repo docs

Issues

• Closes State of the project? #190

Greptile Summary

Added comprehensive support and triage policy with structured issue templates. The changes establish clear priorities (P0-P3), response targets, and bug reporting requirements. Issue templates now collect essential information (btca version, Bun version, OS/shell, commands, and reproduction steps) aligned with SUPPORT.md requirements. All changes are purely additive with no modifications to existing functionality or breaking changes.

Confidence Score: 5/5

• This PR is safe to merge with no risk
• All changes are documentation-only and purely additive, adding new support policy and issue templates without modifying any code or existing features
• No files require special attention

Important Files Changed

Filename	Overview
.github/ISSUE_TEMPLATE/bug_report.yml	Added structured bug report template collecting version, environment, and reproduction details
.github/ISSUE_TEMPLATE/config.yml	Added issue template configuration linking to support policy
.github/ISSUE_TEMPLATE/feature_request.yml	Added structured feature request template with problem statement and proposed solution fields
README.md	Added Support section linking to SUPPORT.md for triage and bug reporting guidance
SUPPORT.md	Added comprehensive support policy defining priorities, response targets, and bug reporting requirements

_{Last reviewed commit: d4764d2}