all: apply godoc [Name] link conventions across comments

Every Go-identifier reference in // and /* */ comments now uses
godoc's [Name] linking syntax so pkg.go.dev and `go doc` render
them as clickable cross-references. No behaviour change.

Pattern applied across the tree:
  In-package         [Foo], [Foo.Bar]
  Cross-package      [pkg.Foo], [pkg.Foo.Bar]
  Stdlib             [netip.Prefix], [errors.Is], [context.Context]
  Tailscale          [tailcfg.MapResponse], [tailcfg.Node.CapMap],
                     [tailcfg.NodeAttrSuggestExitNode]

Skip rules:
  - File:line refs left as plain text
  - HuJSON wire keys inside backtick raw strings untouched
  - ACL/policy syntax tokens (tag:foo, autogroup:self, ...) not Go
    symbols, left as plain text
  - JSON/OIDC wire keys, gorm tags, RFC IPv6 placeholders, markdown
    link tags, decorative dividers — all left as-is

.github/workflows/gh-action-integration-generator.go

@@ -14,7 +14,7 @@ import (
 // Key is the test function name, value is a list of subtest prefixes.
 // Each prefix becomes a separate CI job as "TestName/prefix".
 //
-// Example: TestAutoApproveMultiNetwork has subtests like:
+// Example: [TestAutoApproveMultiNetwork] has subtests like:
 //   - TestAutoApproveMultiNetwork/authkey-tag-advertiseduringup-false-pol-database
 //   - TestAutoApproveMultiNetwork/webauth-user-advertiseduringup-true-pol-file
 //