Apply Development Effort Calculator to real pilot candidates (WP-0010-T03)

Adds since/until date-range scoping to cluster_commit_hours() and
workplan_task_counts() (threaded through calculate_target_basis()),
needed whenever a candidate is one bounded workplan within a repo
whose overall history spans much more (net-kingdom, railiance-apps)
rather than the whole repo being the candidate (vergabe-teilnahme,
info-tech-canon).

Fixes a real bug found along the way: workplan_task_counts() only
scanned the top level of workplans/, missing net-kingdom's
workplans/archived/ convention entirely - silently reported zero
finished workplans for NK-WP-0002, which lives there. Fixed to scan
recursively; added a regression test.

Updates all three draft pilot-candidate manifests with calculator-
derived target_basis/initial_target values, replacing the hand-picked
placeholders:
  net-kingdom-local-identity:      200,000 -> 10,000 EUR (floor + sanity warnings)
  railiance-vergabe-teilnahme:   3,500,000 -> 648,800 EUR (no warnings)
  info-tech-canon-service-surface: 2,500,000 -> 141,800 EUR (sanity warning)

history/260730-EffortCalculator-CandidateApplication.md records full
derivation, warnings, and the judgment calls made explicit rather than
silently picked (date-scoping windows; measuring vergabe-teilnahme's
own repo rather than railiance-apps' deployment-only wiring, with both
figures shown). Still draft/non-binding - WP-0008-T05 unaffected.

5 new tests (20 -> now covering since/until scoping and the
archived-subdirectory fix). Full suite: 84 passing offline.

tests/test_effort_calculator.py

@@ -86,6 +86,27 @@ def test_cluster_commit_hours_gap_splits_into_two_sessions(git_repo):
 # --- workplan_task_counts ------------------------------------------------
 
 
+def test_workplan_task_counts_scans_archived_subdirectory(tmp_path):
+    archived = tmp_path / "workplans" / "archived"
+    archived.mkdir(parents=True)
+    (archived / "old-finished.md").write_text(
+        """---
+id: OLD-0001
+status: finished
+---
+
+```task
+id: OLD-0001-T01
+status: done
+```
+"""
+    )
+    result = ec.workplan_task_counts(tmp_path)
+    assert result.finished_workplans == 1
+    assert result.total_tasks == 1
+    assert result.finished_tasks == 1
+
+
 def test_workplan_task_counts_no_workplans_dir(tmp_path):
     result = ec.workplan_task_counts(tmp_path)
     assert result == ec.WorkplanTaskCounts(0, 0, 0)
@@ -244,3 +265,78 @@ def test_calculate_target_basis_end_to_end(git_repo):
         ec.token_cost_usd(1000, 1000), abs=0.01
     )
     assert isinstance(result.estimated_effort_days, float)
+
+
+# --- since/until date-range scoping ---------------------------------------
+
+
+def test_cluster_commit_hours_since_until_excludes_outside_window(git_repo):
+    _commit(git_repo, "outside-early", 1_577_836_800)  # 2020-01-01
+    _commit(git_repo, "inside", 1_614_556_800)  # 2021-03-01
+    _commit(git_repo, "outside-late", 1_672_531_200)  # 2023-01-01
+    result = ec.cluster_commit_hours(git_repo, since="2021-01-01", until="2021-06-01")
+    assert result.commit_count == 1
+
+
+def test_workplan_task_counts_since_until_filters_by_updated_date(tmp_path):
+    workplans = tmp_path / "workplans"
+    workplans.mkdir()
+    (workplans / "old.md").write_text(
+        """---
+id: OLD-0001
+status: finished
+updated: "2020-01-01"
+---
+
+```task
+id: OLD-0001-T01
+status: done
+```
+"""
+    )
+    (workplans / "recent.md").write_text(
+        """---
+id: NEW-0001
+status: finished
+updated: "2026-03-03"
+---
+
+```task
+id: NEW-0001-T01
+status: done
+```
+"""
+    )
+    result = ec.workplan_task_counts(tmp_path, since="2026-01-01", until="2026-06-01")
+    assert result.finished_workplans == 1
+    assert result.total_tasks == 1
+
+
+def test_workplan_task_counts_no_date_field_always_counted(tmp_path):
+    workplans = tmp_path / "workplans"
+    workplans.mkdir()
+    (workplans / "undated.md").write_text(
+        """---
+id: UND-0001
+status: finished
+---
+
+```task
+id: UND-0001-T01
+status: done
+```
+"""
+    )
+    result = ec.workplan_task_counts(tmp_path, since="2026-01-01", until="2026-06-01")
+    assert result.finished_workplans == 1
+    assert result.total_tasks == 1
+
+
+def test_calculate_target_basis_threads_since_until(git_repo):
+    base = 1_577_836_800  # 2020-01-01
+    _commit(git_repo, "outside", base)
+    _commit(git_repo, "inside", base + 86400 * 400)  # ~2021-02-04
+    result = ec.calculate_target_basis(
+        git_repo, daily_rate=1000.0, since="2021-01-01", until="2021-06-01"
+    )
+    assert result.derivation["commits"] == 1