fix(channelbridge): IM 发送过滤 action/narration + <p>拆多气泡 + 0.5-2s 间隔

把回复转发给 IM 适配器(sendReply)时剥掉 <action>/<narration> 动作/内心独白(Web 端
才渲染灰斜体，IM 只能收纯文本)，并按 <p> 段落拆成多条气泡分别发送；多气泡发送间隔
随机 0.5~2s(仅 IM，Web 前端不延迟)。新增 sanitize.go stripNarration/splitBubbles/
bubbleGap + 测试。

internal/services/channelbridge/sanitize.go

@@ -0,0 +1,81 @@
+package channelbridge
+
+import (
+	"math/rand"
+	"regexp"
+	"strings"
+	"time"
+)
+
+// This file holds the chat-reply sanitizer used before a reply is delivered to an
+// IM channel adapter (design/17 §2 + the role-play convention: the Web client
+// renders <action>/<narration> as muted italic; IM channels must receive plain chat
+// text only, with the action/monologue markup removed).
+
+var (
+	// pairedRoleplayRe matches a complete <action>...</action> / <narration>...</narration>
+	// block including its inner text, so an action/monologue is dropped wholesale before
+	// IM delivery. Non-greedy and case-insensitive to tolerate a model that emits <Action>.
+	pairedRoleplayRe = regexp.MustCompile(`(?is)<(action|narration)\b[^>]*?>.*?</(action|narration)\s*>`)
+	// strayRoleplayRe matches any remaining single opening/closing role-play tag (for a
+	// malformed or unpaired emission).
+	strayRoleplayRe = regexp.MustCompile(`(?is)</?(action|narration)\b[^>]*?>`)
+	// paragraphRe matches <p>...</p> / <p/> paragraph markers, keeping the inner text.
+	paragraphRe = regexp.MustCompile(`(?is)</?p\b[^>]*?>`)
+	// blankLinesRe collapses runs of blank lines left behind after stripping.
+	blankLinesRe = regexp.MustCompile(`\n\s*\n+`)
+)
+
+// stripNarration returns the plain chat text of a reply with role-play/action/
+// narration markup removed, paragraph markers flattened and blank-line runs
+// collapsed. It never raises or panics on malformed input; a reply that was only an
+// action/monologue becomes an empty string (caller may then skip the send).
+func stripNarration(text string) string {
+	if strings.TrimSpace(text) == "" {
+		return ""
+	}
+	s := pairedRoleplayRe.ReplaceAllString(text, "")
+	s = strayRoleplayRe.ReplaceAllString(s, "")
+	s = paragraphRe.ReplaceAllString(s, "")
+	s = blankLinesRe.ReplaceAllString(s, "\n")
+	return strings.TrimSpace(s)
+}
+
+// paragraphBlockRe matches an entire <p>...</p> block, capturing its inner text
+// (design: each <p> is one chat bubble; the Web client renders each as its own
+// bubble and the IM adapters deliver each as its own message).
+var paragraphBlockRe = regexp.MustCompile(`(?is)<p\b[^>]*?>(.*?)</p\s*>`)
+
+// splitBubbles turns a reply into the list of chat bubbles it carries, in order.
+// Each <p>...</p> block is one bubble, with role-play/action/narration stripped from
+// its text; empty bubbles are dropped. A reply with no <p> markers is treated as a
+// single bubble (newlines preserved). A pure action/monologue yields an empty slice.
+func splitBubbles(text string) []string {
+	if !strings.Contains(strings.ToLower(text), "<p") {
+		if c := stripNarration(text); c != "" {
+			return []string{c}
+		}
+		return nil
+	}
+	out := make([]string, 0)
+	for _, m := range paragraphBlockRe.FindAllStringSubmatch(text, -1) {
+		if c := stripNarration(m[1]); c != "" {
+			out = append(out, c)
+		}
+	}
+	if len(out) == 0 {
+		// <p> markers present but no well-formed block — fall back to whole text.
+		if c := stripNarration(text); c != "" {
+			out = append(out, c)
+		}
+	}
+	return out
+}
+
+// bubbleGap returns a randomized 0.5s..2s delay used between IM outbound bubbles so a
+// burst of paragraphs doesn't flood the channel (design/17 §2). The Web frontend is
+// not affected — it renders all bubbles from the persisted stream without any delay.
+// It is only consulted when a reply carries more than one bubble.
+func bubbleGap() time.Duration {
+	return 500*time.Millisecond + time.Duration(rand.Float64()*1500)*time.Millisecond
+}