refactor: DRY auth path, fix Sprintf/RE2 bugs; real integration tests only

Why
---
- Sprintf(*p.Title) fed the title as a format string — % in titles broke
  the String() method; also panicked on nil Title.
- internal/applications.buildSummary used RE2-unsupported `(?= ...)`
  lookahead inside regexp.MustCompile, panicking the first time the
  applications-sync path was exercised on Go 1.23+.
- Query() duplicated the auth-expiry check inline while ensureToken()
  already handled it — two code paths drifted.
- Request.Debug split Query() into two branches that both unmarshalled
  into the same target value. Dead code.
- httptest fixtures that emulated OnlyOffice endpoints were lying to us:
  they passed locally yet never caught a single real protocol regression.

What
----
- Project.String(): nil-safe, no Sprintf format-string interpretation.
- buildSummary regex: RE2-safe non-capturing trailing delimiter
  `(?:\n## |$)` replaces the lookahead.
- Query() routes through ensureToken(); body marshalling factored into
  an unexported requestBodyReader(). Debug flag retained for backwards
  compatibility, documented as a no-op, to be removed at next major.
- Dropped Debug: true stray flags in GetTasks/UpdateProjectTask.
- Deleted httptest-based OnlyOffice mocks. unit_test.go is now pure Go
  (parsers, helpers, env aliases, ctx cancellation against an unroutable
  address). client_test.go is `//go:build integration` and runs against
  a real OnlyOffice, skipping cleanly without ONLYOFFICE_URL/USER/PASS.
- AGENTS.md + .cursor/rules/no-synthetic-mocks.mdc document the new
  testing policy.

Verified
--------
- `go test ./...` green (15 unit tests across package + internal).
- `go test -tags=integration ./...` green against live
  office.produktor.io (5 integration tests: auth, projects, lifecycle,
  calendar+CRM read, task list).
- inventar-sync smoke dry-run against live OO project 33 + Gitea found
  30 tasks, 0 mutations.

Made-with: Cursor

CHANGELOG.md

@@ -6,6 +6,38 @@ adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+## [0.3.2] - 2026-04-24
+
+### Fixed
+
+- `Project.String()` no longer interprets the title as a format string
+  (`fmt.Sprintf(*p.Title)`) and is now nil-safe on a zero-value `Project`.
+- `internal/applications.buildSummary` no longer panics at regex compile time
+  on Go 1.23+ — the previous `(?= ...)` lookahead is replaced with an RE2-safe
+  non-capturing trailing delimiter.
+
+### Changed
+
+- `Client.Query` now routes token acquisition through the shared
+  `ensureToken` path instead of duplicating the auth-expiry check inline.
+- Request body marshalling is consolidated into an unexported
+  `requestBodyReader` helper (DRY; no change to the public surface).
+- The `Request.Debug` field is preserved for backwards compatibility but no
+  longer changes behaviour — both branches used to unmarshal into the same
+  target value. We'll remove the field in a future major release.
+
+### Tests
+
+- Deleted `httptest.NewServer` fixtures that emulated OnlyOffice protocol
+  endpoints. Replaced them with:
+  - pure-Go unit tests in `unit_test.go` (no network);
+  - real integration tests in `client_test.go` guarded by
+    `//go:build integration`. Run with
+    `go test -tags=integration ./...`. Tests skip cleanly when
+    `ONLYOFFICE_URL/USER/PASS` (or aliases) are absent.
+- New policy documented in `AGENTS.md` and
+  `.cursor/rules/no-synthetic-mocks.mdc`.
+
 ## [0.3.1] - 2026-04-24
 
 ### Added