fix(P01): replace hardcoded phase=1 in orchestrator and fix getDecisions double-fetch

---ci---
project: ci
phase: 1
milestone: v0.8
status: in_progress
decisions:
  - id: D-021
    decision: 6-phase wave-ordered vertical slices for v0.8
    rationale: Each phase independently demoable; critical fixes first
    confidence: 0.90
requirements:
  covered: [FIX-01, FIX-06]
---/ci---

FIX-01: Replace 5 hardcoded phase=1 literals in orchestrator.ts mechanical
execution path with this.pipelineState!.current_phase. The orchestrator
correctly tracks current_phase but commits always embedded literal 1.

FIX-06: Replace getDecisions() redundant double-fetch with single
getRecentCommits(50) call, delegating to existing getDecisionsFromCommits().
Old code called getRecentCommits(50) once per grep match entry (O(N*M)
when it should be O(1)).

src/core/git-context.ts

@@ -185,26 +185,8 @@ export class GitContext {
   }
 
   getDecisions(phase?: number): CommitDecision[] {
-    const grepArg = phase !== undefined ? `--grep="phase: ${phase}"` : '--grep="decisions:"';
-    const raw = this.git(`log --all ${grepArg} --format="%B%x01"`);
-
-    if (!raw) return [];
-
-    const decisions: CommitDecision[] = [];
-    const entries = raw.split("\x01").filter(Boolean);
-
-    for (const entry of entries) {
-      const commits = this.getRecentCommits(50);
-      for (const commit of commits) {
-        if (commit.ci?.decisions) {
-          if (phase === undefined || commit.ci.phase === phase) {
-            decisions.push(...commit.ci.decisions);
-          }
-        }
-      }
-    }
-
-    return decisions;
+    const commits = this.getRecentCommits(50);
+    return this.getDecisionsFromCommits(commits, phase);
   }
 
   getDecisionsFromCommits(commits: ParsedCIAgentCommit[], phase?: number): CommitDecision[] {