Add EPG match confidence and explanation details

[rroy676]

Goal

Add EPG match confidence and explanation details so users can understand why Stationarr matched a playlist channel to a specific EPG/scraper channel.

Problem

Wrong or confusing EPG matching is a common IPTV pain point. Users need to know whether a match is reliable before applying it, especially with large playlists, duplicate channel names, SD/HD variants, and regional versions.

Expected behaviour

When Stationarr suggests or applies an EPG match, show a confidence level and a short explanation.

Suggested confidence levels:

High
Medium
Low
Manual

Suggested explanation examples:

Matched by exact tvg-id
Matched by normalized channel name
Matched by name and country
Matched by fuzzy name similarity
Matched by scraper site_id
Low confidence: name only, no country/site confirmation

Suggested UI

In the Channel Editor, Auto Match results, and future Add from Playlist scraper workflow:

Playlist channel      Suggested EPG      Confidence      Why
ESPN HD               ESPN.us            High            Exact normalized tvg-id/name match
A&E                   AETV.us            Medium          Similar name and US country match
Sky Sports Main Event SkySportsMain...   Low             Fuzzy name match only

Requirements

• Show confidence before bulk-applying suggested matches where practical.
• Let users manually override low-confidence matches.
• Store or display the reason for the match if practical.
• Do not silently apply low-confidence bulk matches unless the user confirms.
• Support future use in Add scraper channel suggestions from playlist channels #40 scraper channel suggestions from playlist channels.

Validation

• Run auto-match on a playlist with known EPG IDs.
• Confirm high-confidence matches are identified clearly.
• Confirm weak/fuzzy matches show lower confidence.
• Confirm the user can review and override matches before applying.

Related

Related to #40 scraper channel suggestions from playlist channels, #38 scraper XMLTV normalization, and #54 duplicate channel cleanup.