chore(github): add detailed issue & PR templates, capitalize title prefixes

Adds five new issue templates (bug_report_detailed, feature_request_detailed,
performance_regression, documentation, question) alongside the existing
short forms, plus an optional detailed PR template under
.github/PULL_REQUEST_TEMPLATE/ that contributors can opt into via the
?template=detailed.md URL. Existing templates keep their behavior; only
title prefixes and prose-paren wording were capitalized for consistency.

.github/ISSUE_TEMPLATE/feature_request_detailed.md

@@ -0,0 +1,55 @@
+---
+name: Feature request (Detailed)
+about: Long-form proposal with API sketch, scope checkboxes, prior-art links, and contribution intent.
+title: "[Feat] <short description>"
+labels: ["enhancement", "triage"]
+assignees: []
+---
+
+## Problem / motivation
+
+<!--
+What are you trying to do that Wickra doesn't support today?
+Describe the user-facing pain point, not the implementation.
+-->
+
+## Proposed solution
+
+<!--
+Sketch the API or behavior you'd like. A short code snippet of how
+you'd want to call it is worth a thousand words.
+-->
+
+```python
+import wickra as ta
+
+# proposed API
+ind = ta.SuperTrend(period=10, multiplier=3.0)
+ind.update(close, high, low)
+```
+
+## Scope
+
+- [ ] New indicator
+- [ ] New method on an existing indicator
+- [ ] New binding / platform target
+- [ ] Performance improvement
+- [ ] Ergonomics / API cleanup
+- [ ] Other (Explain below)
+
+## Reference / prior art
+
+<!--
+Link the paper, book chapter, TA-Lib function, TradingView Pine source,
+or other implementations you'd like Wickra to match.
+-->
+
+## Alternatives considered
+
+<!-- What workarounds exist today? Why aren't they enough? -->
+
+## Willingness to contribute
+
+- [ ] I'd like to implement this myself with guidance
+- [ ] I can help review / test
+- [ ] Requesting only — no bandwidth to implement