Add autosolve actions for automated issue resolution

[fantapop]

Summary

Go implementation of composite actions for Claude-powered automated issue resolution:

• autosolve/assess — Runs Claude in read-only mode to evaluate whether a task is suitable for automated resolution
• autosolve/implement — Runs Claude to implement a solution, validates changes, runs AI security review, pushes to a fork, and creates a draft PR

Key features

• Precompiled Go binary (no Go toolchain needed at runtime)
• Per-file batched AI security review with generated-file detection
• Token usage tracking across phases with combined markdown summary
• Retry logic with Claude session resumption
• Skill file support for custom prompts

Testing

Tested end-to-end against cockroachlabs/ccloud-private-automation-testing.

Test plan

• go test ./... passes
• Precompiled binary check passes in CI

[Copilot]

Pull request overview

This PR introduces a new autosolve Go-based automation tool and two composite GitHub Actions (autosolve/assess and autosolve/implement) to assess issue suitability and implement fixes with Claude, including PR creation, security checks, and usage tracking.

Changes:

• Add Go implementation for assessment/implementation orchestration, prompt assembly, git/gh wrappers, and security checks.
• Add composite actions (autosolve/assess, autosolve/implement) plus CI updates to run Go tests and validate the precompiled binary.
• Add prompt templates and unit tests for core functionality.

Reviewed changes

Copilot reviewed 28 out of 30 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
autosolve/internal/security/security_test.go	Adds unit tests for blocked-path and sensitive-file enforcement and .gitignore warnings.
autosolve/internal/security/security.go	Implements blocked path checks, sensitive filename/extension detection, and symlink-to-blocked-path detection.
autosolve/internal/prompt/templates/security-preamble.md	Adds system preamble intended to constrain the model’s behavior for safety.
autosolve/internal/prompt/templates/implementation-footer.md	Adds implementation-phase instruction footer and required success/fail marker.
autosolve/internal/prompt/templates/assessment-footer.md	Adds assessment-phase instruction footer and required proceed/skip marker.
autosolve/internal/prompt/prompt_test.go	Adds tests for prompt construction, skill file inclusion, and custom criteria.
autosolve/internal/prompt/prompt.go	Implements prompt assembly from templates + task inputs.
autosolve/internal/implement/implement_test.go	Adds tests for retry logic, output writing, and summary extraction.
autosolve/internal/implement/implement.go	Implements the implementation phase: retries, security checks, staging/commit/push, PR creation, and AI security review.
autosolve/internal/github/github.go	Adds a gh-CLI-backed GitHub client for comments/labels/PR creation.
autosolve/internal/git/git.go	Adds a git CLI abstraction and helper to list changed files.
autosolve/internal/config/config_test.go	Adds tests for config parsing/validation and blocked path parsing.
autosolve/internal/config/config.go	Adds config loading/validation from action inputs and auth validation.
autosolve/internal/claude/claude_test.go	Adds tests for extracting markers/session IDs and usage tracking.
autosolve/internal/claude/claude.go	Adds Claude CLI runner + result parsing + usage tracking persistence.
autosolve/internal/assess/assess_test.go	Adds tests for assessment flow and summary extraction.
autosolve/internal/assess/assess.go	Implements assessment phase invocation and outputs/summary writing.
autosolve/internal/action/action_test.go	Adds tests for GitHub Actions output and step summary helpers.
autosolve/internal/action/action.go	Adds helpers for outputs, summaries, and workflow annotations.
autosolve/implement/action.yml	Defines the composite action to run autosolve implement and expose outputs.
autosolve/go.mod	Introduces the autosolve Go module definition.
autosolve/cmd/autosolve/main.go	Adds CLI entrypoint for assess and implement commands.
autosolve/build.sh	Adds cross-compile script producing the committed Linux binary.
autosolve/assess/action.yml	Defines the composite action to run autosolve assess and expose outputs.
autosolve/Makefile	Adds build/test/clean targets for local development and CI.
autosolve/.gitignore	Ignores the local dev binary output.
CHANGELOG.md	Documents the addition of the autosolve actions.
.github/workflows/test.yml	Updates CI to run Go tests and ensure the precompiled binary is up to date.

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[fantapop]

One thing I'm running into here is that build the action and committing it each time easily gets out of date and is annoying. I'm going to look into alternatives.