test(cli): cover Spring route callers regression (#1442)

[colbymchenry]

Qualified Spring controller lookups could report no route callers even while node and downstream impact showed the handler and route. The old CLI compared Class.method to bare symbol names, then used the first full-text search hit. An uncalled startFlowExcelCdPreview can outrank startFlowExcelCd, reproducing the two-controller asymmetry in #1442.

The runtime fix is already merged in #1801 (8c9c4761): callers resolve the requested definition through the shared symbol lookup. This PR adds four Spring regression tests using a fresh SQLite index and the built CLI, plus an issue-specific Unreleased note. The tests check both directions of each route/handler edge, node, downstream impact, and text/JSON callers for each controller.

Verified on Linux x64 with Node 22.19.0:

• The identical regression file on v1.5.0 and the parent of fix(cli): group callers/callees/impact by definition (#1512) #1801 (71d049cd): 3 pass, 1 fails, precisely the second controller's empty callers.
• At fix(cli): group callers/callees/impact by definition (#1512) #1801's exact merge commit (8c9c4761) and current main: 4 pass. Both stored route edges, node, and impact are correct in the failing build too.
• npm run build passes.
• Full suite: 4,563 pass, 26 fail, 11 skip; all 26 failures reproduce on unchanged main (3193800b), with identical failing-test names. The Spring regression, framework extraction/integration, symbol lookup, and CLI definition-grouping suites all pass (231 tests).

Issue #1442 predates v1.6.0 and #1801; the behavioral fix is merged but unreleased. The reproduction matches all reported symptoms, although the reporter's full application source was not provided.