style: apply gofmt

Estate-wide consolidation pass. golangci-lint v2 default set enables NO
formatter, so gofmt drift accumulated silently across the estate -- 8 repos
were carrying it, this one included. Same hole that let two files rot in
dma-cli until they were found by hand (dma-cli#12).

Mechanical and deterministic: `gofmt -w`, nothing hand-edited. Verified
before commit -- gofmt -l now reports 0, go build and go vet both pass.

Clears this repo to adopt the canonical .golangci.yml (infra
ci-templates/golangci.yml, infra#309 pattern) in a later wave.

internal/session/history_test.go

@@ -20,8 +20,8 @@ func TestFormatHistoryFormatsEntries(t *testing.T) {
 	entries := []session.Entry{
 		{
 			Skill: "tdd", Phase: "red", FinalStatus: "pass",
-			FilePath: "internal/foo/foo_test.go",
-			Message:  "wrote failing test for Foo",
+			FilePath:  "internal/foo/foo_test.go",
+			Message:   "wrote failing test for Foo",
 			Timestamp: time.Now(),
 		},
 	}

internal/session/session.go

@@ -32,12 +32,12 @@ type Entry struct {
 type Attempt struct {
 	Attempt       int    `json:"attempt"`
 	Model         string `json:"model"`
-	Tier          string `json:"tier"`                    // local | subagent | managed
+	Tier          string `json:"tier"` // local | subagent | managed
 	DurationMs    int64  `json:"duration_ms"`
-	WarmStart     bool   `json:"warm_start"`              // model already loaded in llama-swap
+	WarmStart     bool   `json:"warm_start"` // model already loaded in llama-swap
 	Verified      bool   `json:"verified"`
-	Verdict       string `json:"verdict,omitempty"`       // accept | escalate | error
-	Feedback      string `json:"feedback,omitempty"`      // verifier feedback on escalation
+	Verdict       string `json:"verdict,omitempty"`  // accept | escalate | error
+	Feedback      string `json:"feedback,omitempty"` // verifier feedback on escalation
 	OutputSummary string `json:"output_summary,omitempty"`
 	RunnerOutput  string `json:"runner_output,omitempty"`
 }