[Repo Assist] docs: add package-level godoc comments to all packages; enable revive package-comments rule

[github-actions]

🤖 This PR was created by Repo Assist, an automated AI assistant.

Summary

This PR improves code discoverability and documentation tooling by adding package-level // Package ... doc comments to all 11 internal packages that previously lacked them. It also enables the revive linter's package-comments rule so any future missing package docs are caught by CI.

Changes

Task 5 – Coding Improvements: Package godoc comments

Six packages got new doc.go files, five packages had comments added to their primary file:

Package	Approach
internal/difc	new doc.go
internal/launcher	new doc.go
internal/mcp	new doc.go
internal/middleware	new doc.go
internal/server	new doc.go
internal/testutil/mcptest	new doc.go
internal/envutil	added to envutil.go
internal/strutil	added to deduplicate.go
internal/sys	added to sys.go
internal/timeutil	added to format.go
internal/version	added to version.go

Packages that already had docs (auth, cmd, config, guard, logger, proxy, tty) are untouched.

Task 4 – Engineering Investment: Enable revive package-comments rule

Updated .golangci.yml to:

• Remove revive from the disable list
• Add it to enable with only the package-comments rule configured

This is a scoped enablement — only the package-comments rule runs, so no existing code is flagged for unrelated revive issues.

Rationale

• go doc, pkgsite, and IDE tooling all surface package-level docs prominently; without them these packages appear undocumented to users and contributors.
• The revive package-comments rule enforces this going forward with zero false-positive risk (it only fires when the doc is entirely absent).
• This was tracked as future work in Repo Assist memory.

Test Status

The changes are purely additive (new doc comments and a linter config tweak). No logic is modified. The environment does not have network access to download Go modules, so the full test suite could not be executed locally. CI will verify correctness on push.

The go build ./... command succeeded with the installed Go 1.25.8 toolchain, confirming there are no syntax errors in the new files.

Generated by Repo Assist · ◷

To install this agentic workflow, run

gh aw add githubnext/agentics/workflows/repo-assist.md@851905c06e905bf362a9f6cc54f912e3df747d55

Warning

⚠️ Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

• proxy.golang.org

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "proxy.golang.org"

See Network Configuration for more information.