v3 workflow: intent, phases, review, submission, enforcement, burn-in

The v3 stack, previously an uncommitted working tree, plus this session's two
units and the burn-in instrument. This commit is the burn-in build identity:
coordinator and worker must both report this revision before a task is created.

Workflow (earlier sessions, uncommitted until now): human decision events and
reduction, source cursors and reconcile-before-launch, turn-boundary
reconciliation, internal/agentctx as the single renderer, ace-fca phases with
sealed artifacts, the trajectory gate, bounded grilling, independent review,
task pr enforcement, and human review reflection.

Capability restrictions at the agent boundary: an authz.Agent surface at
GatedWrite may ask and may not act. It also fixes two bugs the unit exposed --
gated surfaces could not reach the two endpoints written for them, and
RequestHumanDecision would block an unowned task while rejecting a question
from the session that did own it.

Turn-boundary reconcile-failure escalation: a streak of consecutive failures
asks the session to hand off, fenced on the lease epoch, with reconcile_failure
as a real handoff reason. The worker was dropping the coordinator's verdict on
the floor; it now acts on it.

Burn-in: herdr.WriteLaunchContext dumps the exact agentctx.Build result to
<worktree>/.orchestra/launch.md at every launch, local and federated. BURNIN.md
is the runbook. deploy/build.sh stamps both binaries from one commit.

go build, go vet and go test ./... pass, 20 packages.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

internal/continuity/continuity.go

@@ -129,7 +129,10 @@ type Result struct {
 	AtSHA    string `json:"at_sha"`
 }
 
-var reasons = map[string]bool{"threshold": true, "milestone": true, "thrash": true, "manual": true}
+// reconcile_failure is Orchestra's own trigger: human input could not be
+// reconciled at repeated verified turn boundaries, so the session is handed to
+// a successor rather than left running on intent that cannot be refreshed.
+var reasons = map[string]bool{"threshold": true, "milestone": true, "thrash": true, "manual": true, "reconcile_failure": true}
 
 const maxAuthoredLine = 200