[BUG] TXT export uses generateMarkdown() — outputs markdown syntax instead of plain text #359

📌 Bug Description

The "Export as TXT" button in the dashboard export dropdown calls generateMarkdown(state) and saves the result as a .txt file. The output contains markdown formatting syntax (#, **, - [ ], _italics_) which is not appropriate for a plain text file.

Affected file: src/dashboard.ts — lines 1038–1052

// --- TXT EXPORT (LIVE DASHBOARD) ---
document.getElementById("export-txt-btn")?.addEventListener("click", async () => {
  try {
    const state = await chrome.runtime.sendMessage({ type: "GET_STATE" });
    if (!state) throw new Error("No meeting data available");
    const textContent = generateMarkdown(state); // <-- produces markdown, not plain text
    const filename = `meeting-summary-${new Date().toISOString().slice(0, 10)}.txt`;
    downloadFile(textContent, filename, "text/plain");
    showToast("Downloaded as .txt file", "success");
  } catch (err) { ... }
});

The generateMarkdown() function produces output like:

# Meeting Summary — May 31, 2026

**Meeting ID:** abc-defg-hij
**Duration:** 00:45:12

## Action Items
- [ ] Send proposal — Alice
- [x] Review budget — Bob

## Key Decisions
- Approved new tooling _— CTO_

This is markdown, not plain text.

🔄 Steps to Reproduce

1. Start a meeting with Late-Meet and let it capture some transcript
2. Open the dashboard side panel
3. Click "Export Summary" → "Export as TXT"
4. Open the downloaded .txt file
5. Observe markdown syntax characters (#, **, - [ ], _) in the output

✅ Expected Behavior

The TXT export should produce clean plain text without any markdown formatting:

Meeting Summary — May 31, 2026

Meeting ID: abc-defg-hij
Duration: 00:45:12

Action Items
• Send proposal — Alice (done)
• Review budget — Bob

Key Decisions
• Approved new tooling — CTO

❌ Actual Behavior

The TXT file contains raw markdown syntax that renders as formatting noise when opened in Notepad, TextEdit, or any plain text viewer.

💻 Environment

• Chrome Version: Any
• Operating System: Any
• Extension Version: 1.2.0
• Transcription Provider: N/A (export feature issue)

🛠️ Suggested Fix

Create a separate generatePlainText(state) function that strips markdown syntax:

• Replace # headers with plain text + newlines
• Replace **bold** with plain text
• Replace - [ ] / - [x] with bullet points and status indicators
• Replace _italics_ with plain text

Or apply a simple post-processing step to strip markdown from the output before saving as TXT.