refactor: rework of issue and pr template and add contributing.md (#998)

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

.github/pull_request_template.md

@@ -0,0 +1,91 @@
+<!--
+  Pull Request Template for Streamyfin
+  ====================================
+  Use this template to help reviewers understand the purpose of your PR
+  and to ensure all necessary checks are completed before merging.
+-->
+
+# 📦 Pull Request
+
+## 🔖 Summary
+<!--
+A concise description of the changes introduced by this PR.
+Example:
+“Add real-time currency conversion widget to dashboard.”
+-->
+
+## 🏷️ Ticket / Issue
+<!--
+Link to the related ticket, issue or user story.
+You can also indicate if this PR supersedes a previous one.
+Example:
+- Closes #123
+- Fixes STREAMYFIN-456
+- Resolves #789
+- Supersedes #120
+- Related: #130
+-->
+
+## 🛠️ What’s Changed
+<!-- Use a Conventional Commit in the PR title, e.g., `feat(auth): add MFA`. 
+If this PR introduces a breaking change, include a `BREAKING CHANGE:` block in the description.
+Spec: https://www.conventionalcommits.org/ -->
+
+- Type: feat | fix | docs | style | refactor | perf | test | chore | build | ci | revert
+- Scope (optional): e.g., auth, billing, mobile
+- Short summary: what changed and why (1–2 lines)
+-->
+
+## 📋 Details
+<!--
+Provide more context or background. Explain any non-obvious decisions.
+Include screenshots or GIFs for UI changes if applicable.
+-->
+
+### ⚠️ Breaking Changes
+<!-- List any breaking API/contract changes and migration guidance. If none, write “None”. -->
+
+### 🔐 Security & Privacy Impact
+<!-- Data touched, new permissions/scopes, PII, secrets, threat considerations. If none, write “None”. -->
+
+### ⚡ Performance Impact
+<!-- Hot paths, memory/CPU/latency implications, benchmarks if available. -->
+
+### 🖼️ Screenshots / GIFs (if UI)
+<!-- Before/After, dark mode, responsive states. -->
+
+## ✅ Checklist
+<!--
+Review and check off items as you complete them.
+-->
+- [ ] I’ve read the [contribution guidelines](CONTRIBUTING.md)
+- [ ] Code follows project style and passes lint/format (`npm|pnpm|yarn|bun` scripts)
+- [ ] Type checks pass (tsc/biome/etc.)
+- [ ] Docs updated (README/ADR/usage/API)
+- [ ] No secrets/credentials included; env vars documented
+- [ ] Release notes/CHANGELOG entry added (if applicable)
+- [ ] Verified locally that changes behave as expected
+
+## 🔍 Testing Instructions
+<!--
+Describe how reviewers can test your changes.
+Example:
+1. `git fetch origin pull/<PR_ID>/head:branchname && git checkout branchname`
+2. Install deps: `npm|pnpm|yarn|bun install`
+3. Start service/app: `npm|pnpm|yarn|bun run [target]` (e.g., `npm run ios` or `bun run android:tv`)
+4. Run tests: `npm|pnpm|yarn|bun test`
+5. Verification steps:
+   - [ ] Expected UI/endpoint behavior
+   - [ ] Logs show no errors
+   - [ ] Edge cases covered (list)
+-->
+
+## ⚙️ Deployment Notes
+<!--
+Describe any deployment considerations such as config, environment vars, or native builds.
+-->
+
+## 📝 Additional Notes
+<!--
+Any other information or references related to this PR.
+-->