feat(capture): remove summary->ai-sessions write path

ai-sessions#13: capture's `summary` field wrote a frontmatter shape
(title/harness/fidelity/captured_at/repos_touched) that ai-sessions'
own extract/audit pipeline can't parse -- silently invisible to that
repo's own audit tooling, and bypassing its redaction + Stage2
completeness gates by construction. Only 5 files ever landed this way
over 3 weeks; the summary capability's whole value (speed) fights
ai-sessions' whole value (redacted, audited, complete), so kill it
rather than build a second parse branch.

capture now persists insights -> brain and action items -> Gitea
tickets only. Removes Summary/SummaryResult/SummaryWriter and all
wiring (service, REST body, MCP tool schema); close-session updated to
stop assembling a summary payload. specs/capture-*.md kept as historical
record with a superseded note -- the feature shipped and is documented,
just no longer current behaviour.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WPdSHbp9Utb2hPFm9wDG59

ingestion/internal/capture/entities.go

@@ -1,8 +1,7 @@
 // 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.
+// valuable output — insights → brain, action items → Gitea tickets —
+// 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
@@ -83,19 +82,11 @@ type Ticket struct {
 	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
 }
 
@@ -117,12 +108,6 @@ type TicketResult struct {
 	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 {
@@ -136,7 +121,6 @@ type ItemError struct {
 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"`