fix file sharing bug (#6161)

# Description of Changes

Fixes share-link navigation for SSO users. Reported on v2.9.2 with
`SSOAutoLogin: true`: clicking a `/share/<token>` link in an email
redirected the user to the home page after SSO instead of the shared
file.

## Root cause

Three compounding issues had to be fixed together; the first was the
initial symptom but the other two only surfaced during live
verification.

1. **Spring Security blocked `/share/<token>` for unauthenticated
users.** The route wasn't in `RequestUriUtils.isPublicAuthEndpoint`, so
the server 302'd straight to `/login` before React could load
`ShareLinkPage`. The share URL was lost because `NullRequestCache` is
configured and never persisted the original destination.

2. **`httpErrorHandler` full-page-redirected to `/login?from=<path>` on
any unhandled 401** (fired by `LicenseContext`, `AppConfig`, etc. during
normal ShareLinkPage mount). That *did* preserve the return path — but
**Spring Security strips query strings from `/login`** (302 to bare
`/login`), so `?from=` never reached React. Confirmed via `curl -i
http://localhost:8080/login?from=xyz` → `Location: /login`.

3. **`AuthCallback.tsx` unconditionally `navigate("/")`** after the
SAML/OAuth round-trip, discarding any intended destination.

## Fix

**Backend** — make `/share/<token>` a public SPA bootstrap, data APIs
stay protected:
- `RequestUriUtils.isPublicAuthEndpoint` — permits `^/share/[^/]+/?$`
(tight regex, single token segment only; `/share/<token>/anything` stays
protected).
- `ReactRoutingController` — dedicated `@GetMapping("/share/{token}")`
mirroring `/auth/callback`.
- `/api/v1/storage/share-links/**` remains behind Spring Security with
its existing `canAccessShareLink` check.

**Frontend** — persist the return path across full-page redirects via
`sessionStorage` (same-origin, survives the SSO round-trip):
- `httpErrorHandler.ts` — stashes current pathname to
`stirling_post_login_path` before the 401 → `/login` redirect.
- `springAuthClient.ts` — new `isSafePostLoginRedirect` /
`setPostLoginRedirectPath` / `consumePostLoginRedirectPath` helpers
(rejects protocol-relative URLs and auth-plumbing paths to guard against
open-redirect abuse).
- `Login.tsx` — on explicit user sign-in, read path from
`location.state` or `?from=` query and stash it; don't clobber an
already-stashed value.
- `AuthCallback.tsx` — consume the stashed path (single-use) and
`navigate(target)` instead of always `/`.


---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have run `task check` to verify linters, typechecks, and tests
pass
- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#7-testing)
for more details.

---------

Co-authored-by: EthanHealy01 <[email protected]>

.dockerignore

@@ -1,6 +1,8 @@
 # Version control
 .git/
 .gitignore
+.git-blame-ignore-revs
+.gitattributes
 
 # Build outputs
 build/
@@ -15,22 +17,34 @@ version_builds/
 # Gradle caches (local, not what's in the container)
 .gradle/
 **/.gradle/
+.gradle-home/
+
+# Task (go-task) cache
+.task/
 
 # Node / frontend
 node_modules/
 **/node_modules/
 frontend/node_modules/
 frontend/dist/
+frontend/playwright-report/
 .npm/
 .yarn/
 
 # Tauri/desktop builds
 src-tauri/target/
 src-tauri/dist/
+frontend/src-tauri/target/
+frontend/src-tauri/dist/
 
 # IDE and editor
 .idea/
 .vscode/
+.settings/
+.settings.zip
+.classpath
+.project
+.devcontainer/
 *.iml
 *.ipr
 *.iws
@@ -41,6 +55,7 @@ src-tauri/dist/
 *.pid
 .DS_Store
 Thumbs.db
+logs/
 
 # Docker itself
 Dockerfile*
@@ -54,13 +69,33 @@ Dockerfile*
 # Test reports
 **/test-results/
 **/jacoco/
+test_*.pdf
 
 # Testing and documentation (not needed in build)
 testing/
 docs/
+devGuide/
+devTools/
 *.md
 README*
 
+# Separate projects not consumed by the Java/frontend build
+commonforms-onnx/
+
+# Runtime mount points used by docker-compose volumes, not build input
+stirling/
+customFiles/
+configs/
+
+# Claude Code workspace
+.claude/
+
+# Python caches
+.pytest_cache/
+.ruff_cache/
+__pycache__/
+**/__pycache__/
+
 # Local env
 .env
 .env.*
@@ -73,4 +108,3 @@ README*
 *~
 .DS_Store
 .cache/
-.pytest_cache/