Port of the legacy requirement-spec tree semantics (TestLink 1.9.20 lib/requirements/reqSpecListTree.php + lib/ajax/getrequirementnodes.php?mode=reqspec

• generate_reqspec_tree() / render_reqspec_treenode() / prepare_reqspec_treenode() in lib/functions/treeMenu.inc.php) into the modernized reqSpecMgmt screen (gui/templates/requirements/reqSpecMgmt.html + api/reqspec/index.php).

Before this change the modern screen was a flat DataTable:

• action=specs selected nh.node_order but never nh.parent_id, and the response map emitted neither — a child spec (RS-200 under RS-100) came back as a top-level sibling;
• the Reqs badge was COUNT(*) FROM requirements GROUP BY srs_id, i.e. the direct count, where legacy showed the subtree count (child_req_count in treeMenu.inc.php:1935-1960 adds the counters of every nested child spec);
• the project-wide total (count(get_all_requirement_ids()), tlRequirementFilterControl.class.php:275-280) was not exposed at all;
• no expand/collapse, no indent, no nesting indicator;
• this screen could not create a nested spec: create_spec already accepted parent_id (Refs #1345) but the modal had no parent field.

field	meaning	legacy counterpart
parent_id	hierarchy parent, 0 = top level (test project node / orphan / self-parent / cycle)	nodes_hierarchy.parent_id
node_order	sibling order	position (node_order)
child_specs	number of directly nested specs	— (implicit in the tree)
subtree_reqs	own + all nested child specs requirements	child_req_count, treeMenu.inc.php:2149-2150
req_count	direct requirements only (unchanged, now the tooltip)	—
envelope total_reqs	project subtree total	root node "{$name} ({$req_qty})"
envelope child_requirements_mgmt	req_cfg->child_requirements_mgmt (config.inc.php:1689)	getrequirementnodes.php:46-51 forbidden_parent guard

The subtree counters come from a single post-order pass over the already-loaded rows ($resolve closure, api/reqspec/index.php:658-680), so the whole screen costs one extra query instead of the legacy tree::getAllItemsID() N+1 (one recursive query per visible node).

• orderedSpecTree() does a depth-first walk over parent_id, siblings sorted by node_order then id; a cycle guard prevents an infinite walk.
• The DataTable is created with order: [] + paging: false so the tree order is not destroyed (DataTables otherwise re-sorts by column 0).
• Each spec with children gets a +/- toggle; the toolbar gets Expand all / Collapse all (legacy inc_tree_control.tpl:15-27 tree.expandAll() / tree.collapseAll()).
• Collapsed state is persisted in localStorage per test project (TL_req_spec_mgmt_collapsed_<tproject_id>), mirroring the legacy TreePanelState / LocalStorageProvider cookie prefix scheme.
• The section header shows the legacy root-node count: total requirements in <project>: 4.
• The create modal gained a Parent specification select (dotted-path options, a spec can never be its own parent); the picker is only offered when child_requirements_mgmt is ENABLED and the user may manage specs. A per-row New child specification action pre-fills it.

needOwnedSpec() ended with return @$reqSpecMgr->get_by_id(...). No caller uses the return value — it is purely an existence/ownership guard. But get_by_id() resolves the latest revision through the latest_rspec_revision view and builds ... AND RSPEC_REV.id = with a NULL child id when that row is absent. That is an uncaught database Exception, not a suppressible warning, so @ did nothing and the request died with HTTP 500 / empty body.

Reproduced: POST action=create_spec with parent_id: 0 → 200 {"status":"ok"}, with parent_id: 10 → 500 (empty body, Uncaught Exception: Database error (query failed) … requirement_spec_mgr.class.php(218) … api/reqspec/index.php(138) needOwnedSpec()). This made the entire nested-spec creation path — including the reqSpecView.html "New Child Spec" button shipped with #1345 — unusable. Fix: drop the dead get_by_id() call and return true after the ownership probe.

13 new keys in all 10 locale bundles (de, en, es, fr, it, ja, pt, ro, ru, zh): rs.expandAll, rs.collapseAll, rs.expandNode, rs.collapseNode, rs.treeHint, rs.totalReqsOf, rs.reqsInSubtree, rs.childSpecs, rs.childSpecsShort, rs.newChildSpec, rs.parentSpecLabel, rs.parentSpecHint, rs.parentTopLevel.

file	purpose
api/reqspec/index.php	specs tree model + needOwnedSpec() fix
gui/templates/requirements/reqSpecMgmt.html	tree DataTable, toggles, total line, parent picker
gui/templates/i18n/*.json	13 new keys × 10 locales
CHANGELOG	[FEATURE GAP] - #1026 entry
images/issue-1026-spec-tree.png	the rendered tree

• Task #1028 — spec / requirement detail deep links — the legacy tree node href (REQ_SPEC_MGMT / REQ_MGMT) ported to a per-row eye link into reqSpecView.html / reqView.html, gated on mgt_view_req.