feat(capture): CaptureService use-case + ports + entities (#51)

The Clean-Architecture core of the capture capability (#49b). Pure
orchestration over ports — no HTTP, no live Gitea, no audit I/O — fully
unit-tested against fakes before any adapter exists.

- Ports: BrainStore (#45 write/update/get), IssueTracker, SummaryWriter,
  ClassificationPolicy (satisfied by #50's classification.Config),
  AuditSink. Entities: Insight, Ticket, Summary, CaptureContext,
  CaptureInput, CaptureReceipt.
- CaptureService.Capture: validate-before-write (fail-closed), resolve
  effective classification (stricter of declared vs target-derived;
  under-declaration logged as a security event), orchestrate insights
  (write/supersede) → tickets → summary best-effort, emit a request-level
  audit record of exactly what landed, return a partial-aware receipt.
- dry_run short-circuits after validation, writes nothing (not even audit).

Out of scope here, layered on later: the I1 origin sovereignty gate (#53,
needs the server-derived principal) and the classification-aware audit
degradation/refusal (#54). "Effective" is folded into the service as
classification.Stricter rather than a port method — the stricter-wins
rule is use-case policy.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

ingestion/internal/capture/entities.go

@@ -0,0 +1,111 @@
+// Package capture is the Clean-Architecture use-case for the uniform
+// capture capability (issue #49/#51): persist a finished session's
+// valuable output — insights → brain, action items → Gitea tickets,
+// optional summary → ai-sessions — with one invocation, identical core
+// behaviour across every harness.
+//
+// This package is pure orchestration. It depends only on ports
+// (interfaces) and plain entities — no HTTP, no live Gitea, no embedding
+// or audit I/O. The real adapters are wired in #52 (Gitea tracker), #53
+// (REST + I1 origin gate), and #54/#55 (audit path + relay). The I1
+// sovereignty refusal and the classification-aware audit degradation are
+// deliberately NOT here — those need the server-derived principal origin
+// (#53) and the loki/buffer machinery (#54). What lives here is everything
+// testable against fakes: validation, effective-classification resolution
+// (stricter wins), best-effort orchestration, and the partial receipt.
+package capture
+
+// CaptureContext is the per-session metadata accompanying a capture.
+//
+// Classification is the caller-declared sensitivity (model C, spec §4.1):
+// the server independently derives the target's classification and gates
+// on the stricter of the two. Principal is server-derived from the
+// authenticated identity (#53 populates it); it is never caller-asserted.
+// Harness is descriptive telemetry only — never a gate input.
+type CaptureContext struct {
+	Harness        string
+	SessionRef     string
+	Fidelity       string
+	Actor          string
+	Classification string // caller-declared level token ("" = unspecified)
+	Principal      string // server-derived (auth); audit identity
+}
+
+// Insight is one piece of session knowledge bound for the brain. A
+// non-empty SupersedeSlug routes to Update (revise in place); otherwise
+// Write (create).
+type Insight struct {
+	Text          string
+	Wing          string
+	Hall          string
+	SupersedeSlug string
+}
+
+// Ticket is one action item bound for a Gitea repo. Owner is always the
+// operator (set by the tracker adapter), never carried here.
+type Ticket struct {
+	Repo   string
+	Action string // create | close | comment
+	Number int    // required for close/comment
+	Title  string // required for create
+	Body   string
+}
+
+// Summary is an optional session summary bound for ai-sessions.
+type Summary struct {
+	Title        string
+	Body         string
+	ReposTouched []string
+}
+
+// CaptureInput is the whole capture request.
+type CaptureInput struct {
+	Context  CaptureContext
+	Insights []Insight
+	Tickets  []Ticket
+	Summary  *Summary
+	DryRun   bool
+}
+
+// InsightResult is the per-insight outcome in the receipt.
+type InsightResult struct {
+	ID          string `json:"id,omitempty"`
+	Path        string `json:"path,omitempty"`
+	ContentHash string `json:"content_hash,omitempty"`
+	Superseded  bool   `json:"superseded"`
+	OK          bool   `json:"ok"`
+}
+
+// TicketResult is the per-ticket outcome in the receipt.
+type TicketResult struct {
+	Repo   string `json:"repo"`
+	Number int    `json:"number,omitempty"`
+	Action string `json:"action"`
+	URL    string `json:"url,omitempty"`
+	OK     bool   `json:"ok"`
+}
+
+// SummaryResult is the summary outcome in the receipt.
+type SummaryResult struct {
+	Path string `json:"path,omitempty"`
+	OK   bool   `json:"ok"`
+}
+
+// ItemError pins a failure to a specific request item for the partial
+// receipt. Item is a stable locator like "insight[1]" or "ticket[0]".
+type ItemError struct {
+	Item  string `json:"item"`
+	Error string `json:"error"`
+}
+
+// CaptureReceipt is the structured, partial-aware result. Per-item ok
+// flags plus a flat Errors list make partial success explicit; the
+// caller never has to infer what landed.
+type CaptureReceipt struct {
+	Insights                []InsightResult `json:"insights"`
+	Tickets                 []TicketResult  `json:"tickets"`
+	Summary                 *SummaryResult  `json:"summary,omitempty"`
+	Errors                  []ItemError     `json:"errors"`
+	EffectiveClassification string          `json:"effective_classification,omitempty"`
+	DryRun                  bool            `json:"dry_run"`
+}