[Feature Request] Add time range parameter to /insights command

Bug Description
Title: /insights — add time range parameter

Body:
Currently /insights analyzes all available session data with no scoping. Request: accept a time range argument to scope the report.

Use case: I'm transitioning between workflows (e.g., from EDD-style to a new flow this week). Mixing weeks of EDD sessions with this week's new-flow sessions adds noise — friction points and patterns from the old workflow contaminate the analysis of the new one. Cannot evaluate or compare workflows independently.

Suggested syntax:

• /insights 7d (last 7 days)
• /insights 30d
• /insights since:2026-04-21
• /insights from:YYYY-MM-DD to:YYYY-MM-DD

Workaround attempted: /export + manual filter — heavy for routine retros.

Impact: enables week-over-week retros, A/B comparison of workflows, and onboarding analysis scoped to a learning period.

Environment Info

• Platform: win32
• Terminal: null
• Version: 2.1.116
• Feedback ID: 1645f40a-9604-4b2a-b7dd-dc35830fc98c

Errors

[{"error":"Error: Plugin MCP server error - mcp-config-invalid: MCP server postman invalid: Missing environment variables: POSTMAN_API_KEY\n    at jPH (B:/~BUN/root/src/entrypoints/cli.js:2808:30294)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-28T22:36:42.165Z"},{"error":"Error: Plugin MCP server error - mcp-config-invalid: MCP server github invalid: Missing environment variables: GITHUB_PERSONAL_ACCESS_TOKEN\n    at jPH (B:/~BUN/root/src/entrypoints/cli.js:2808:30294)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-28T22:36:42.165Z"},{"error":"Error: Plugin MCP server error - mcp-config-invalid: MCP server github invalid: Missing environment variables: GITHUB_PERSONAL_ACCESS_TOKEN\n    at jPH (B:/~BUN/root/src/entrypoints/cli.js:2808:30294)\n    at async G (B:/~BUN/root/src/entrypoints/cli.js:6198:11019)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-28T22:36:48.653Z"},{"error":"Error: Plugin MCP server error - mcp-config-invalid: MCP server postman invalid: Missing environment variables: POSTMAN_API_KEY\n    at jPH (B:/~BUN/root/src/entrypoints/cli.js:2808:30294)\n    at async G (B:/~BUN/root/src/entrypoints/cli.js:6198:11019)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-28T22:36:48.653Z"},{"error":"Error: Plugin MCP server error - mcp-config-invalid: MCP server postman invalid: Missing environment variables: POSTMAN_API_KEY\n    at jPH (B:/~BUN/root/src/entrypoints/cli.js:2808:30294)\n    at async v (B:/~BUN/root/src/entrypoints/cli.js:6198:11826)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-28T22:36:48.654Z"},{"error":"Error: Plugin MCP server error - mcp-config-invalid: MCP server github invalid: Missing environment variables: GITHUB_PERSONAL_ACCESS_TOKEN\n    at jPH (B:/~BUN/root/src/entrypoints/cli.js:2808:30294)\n    at async v (B:/~BUN/root/src/entrypoints/cli.js:6198:11826)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-28T22:36:48.654Z"},{"error":"Error: Failed to create shell snapshot: Command failed: C:\\Program Files\\Git\\bin\\bash.exe -c -l SNAPSHOT_FILE='C:\\Users\\Carlitos\\.claude\\shell-snapshots\\snapshot-bash-1777419323255-y9w5vv.sh'\n      source \"C:\\Users\\Carlitos\\.bashrc\" < /dev/null\n\n      # First, create/clear the snapshot file\n      echo \"# Snapshot file\" >| \"$SNAPSHOT_FILE\"\n\n      # When this file is sourced, we first unalias to avoid conflicts\n      # This is necessary because aliases get \"frozen\" inside function definitions at definition time,\n      # which can cause unexpected behavior when functions use commands that conflict with aliases\n      echo \"# Unset all aliases to avoid conflicts with functions\" >> \"$SNAPSHOT_FILE\"\n      echo \"unalias -a 2>/dev/null || true\" >> \"$SNAPSHOT_FILE\"\n\n      \n      echo \"# Functions\" >> \"$SNAPSHOT_FILE\"\n\n      # Force autoload all functions first\n      declare -f > /dev/null 2>&1\n\n      # Now get user function names - filter completion functions (single underscore prefix)\n      # but keep double-underscore helpers (e.g. __zsh_like_cd from mise, __pyenv_init)\n      declare -F | cut -d' ' -f3 | grep -vE '^_[^_]' | while read func; do\n        # Encode the function to base64, preserving all special characters\n        encoded_func=$(declare -f \"$func\" | base64 )\n        # Write the function definition to the snapshot\n        echo \"eval \\\"\\$(echo '$encoded_func' | base64 -d)\\\" > /dev/null 2>&1\" >> \"$SNAPSHOT_FILE\"\n      done\n    \n      echo \"# Shell Options\" >> \"$SNAPSHOT_FILE\"\n      shopt -p | head -n 1000 >> \"$SNAPSHOT_FILE\"\n      set -…

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