feat: Display AI reasoning/thinking blocks in chat interface (#152)

* feat: Add reasoning/thinking blocks display in chat interface

* feat: add multi-provider options support and replace custom reasoning UI with AI Elements

* resolve conflicting reasoning configs and correct provider-specific reasoning parameters

* try to solve conflict

* fix: simplify reasoning display and remove unnecessary dependencies

- Remove Streamdown dependency (~5MB) - reasoning is plain text only
- Fix Bedrock providerOptions merging for Claude reasoning configs
- Remove unsupported DeepSeek reasoning configuration
- Clean up unused environment variables (REASONING_BUDGET_TOKENS, REASONING_EFFORT, DEEPSEEK_REASONING_*)
- Remove dead commented code from route.ts

Reasoning blocks contain plain thinking text and don't need markdown/diagram/code rendering.

* feat: comprehensive reasoning support improvements

Major improvements:
- Auto-enable reasoning display for all supported models
- Fix provider-specific reasoning configurations
- Remove unnecessary Streamdown dependency (~5MB)
- Clean up debug logging

Provider changes:
- OpenAI: Auto-enable reasoningSummary for o1/o3/gpt-5 models
- Google: Auto-enable includeThoughts for Gemini 2.5/3 models
- Bedrock: Restrict reasoningConfig to only Claude/Nova (fixes MiniMax error)
- Ollama: Add thinking support for qwen3-like models

Other improvements:
- Remove ENABLE_REASONING toggle (always enabled)
- Fix Bedrock providerOptions merging for Claude
- Simplify reasoning component (plain text rendering)
- Clean up unused environment variables

* fix: critical bugs and documentation gaps in reasoning support

Critical fixes:
- Fix Bedrock shallow merge bug (deep merge preserves anthropicBeta + reasoningConfig)
- Add parseInt validation with parseIntSafe helper (prevents NaN errors)
- Validate all numeric env vars with min/max ranges

Documentation improvements:
- Add BEDROCK_REASONING_BUDGET_TOKENS and BEDROCK_REASONING_EFFORT to env.example
- Add OLLAMA_ENABLE_THINKING to env.example
- Update JSDoc with accurate env var list and ranges

Code cleanup:
- Remove debug console.log statements from route.ts
- Refactor duplicate providerOptions assignments

---------

Co-authored-by: Dayuan Jiang <34411969+DayuanJiang@users.noreply.github.com>
Co-authored-by: Dayuan Jiang <jdy.toh@gmail.com>

components/ai-elements/shimmer.tsx

@@ -0,0 +1,64 @@
+"use client"
+
+import { motion } from "motion/react"
+import {
+    type CSSProperties,
+    type ElementType,
+    type JSX,
+    memo,
+    useMemo,
+} from "react"
+import { cn } from "@/lib/utils"
+
+export type TextShimmerProps = {
+    children: string
+    as?: ElementType
+    className?: string
+    duration?: number
+    spread?: number
+}
+
+const ShimmerComponent = ({
+    children,
+    as: Component = "p",
+    className,
+    duration = 2,
+    spread = 2,
+}: TextShimmerProps) => {
+    const MotionComponent = motion.create(
+        Component as keyof JSX.IntrinsicElements,
+    )
+
+    const dynamicSpread = useMemo(
+        () => (children?.length ?? 0) * spread,
+        [children, spread],
+    )
+
+    return (
+        <MotionComponent
+            animate={{ backgroundPosition: "0% center" }}
+            className={cn(
+                "relative inline-block bg-[length:250%_100%,auto] bg-clip-text text-transparent",
+                "[--bg:linear-gradient(90deg,#0000_calc(50%-var(--spread)),var(--color-background),#0000_calc(50%+var(--spread)))] [background-repeat:no-repeat,padding-box]",
+                className,
+            )}
+            initial={{ backgroundPosition: "100% center" }}
+            style={
+                {
+                    "--spread": `${dynamicSpread}px`,
+                    backgroundImage:
+                        "var(--bg), linear-gradient(var(--color-muted-foreground), var(--color-muted-foreground))",
+                } as CSSProperties
+            }
+            transition={{
+                repeat: Number.POSITIVE_INFINITY,
+                duration,
+                ease: "linear",
+            }}
+        >
+            {children}
+        </MotionComponent>
+    )
+}
+
+export const Shimmer = memo(ShimmerComponent)