Improvements for TV Logo lookup matching.

[form400]

Improve TV logo matching rate from 23% to ~67%

Summary

This PR addresses poor TV logo matching against the tv-logo/tv-logos
repository. Analysis of a real 616-channel lineup showed only 142 (23%)
of channels were resolving to a logo. After two rounds of investigation,
the matcher now resolves an estimated 414 (67%) — a 3× improvement.

Root cause analysis

Two distinct failure modes were identified by inspecting actual cache
contents and channel metadata:

1. Local broadcast affiliates were generated with the wrong path
   (e.g., abc-7-kabc-us.png instead of us-local/abc-7-kabc-us.png).
2. Cable channels with cryptic callsigns and empty affiliate names
   (93% of the test lineup) were unmatchable — GraceNote sends
   callSign=HISTORY, affiliateName="" but the repo slug is
   history-channel-us.png. Direct slugification produced history.

Changes

Round 1 — 4c4563b improve tv-logo channel matching rate

• Add local-affiliate slug patterns: {network}-{channelNo}-{callsign} and
  {network}-{callsign}
• Fix slugify: & now converts to "and" (was "-"), fixing A&E,
  AT&T SportsNet, etc.
• Fix affiliateAliases: "the weather channel" → weather-channel
  (was incorrectly the-weather-channel)
• Trim noiseWords to stop stripping network, channel, tv,
  entertainment — these words appear in many repo slugs
• Add networkSlugs map for ABC/CBS/NBC/FOX/CW/PBS/Telemundo/Univision
• Add bareCallSign helper stripping both dash-separated (-TV, -DT,
  -HD, -LD) and inline (HD, DT) suffixes
• Reorder candidate generation for higher-precision-first matching
• Thread ChannelNo through guide.Channel and tvlogo.Resolve so
  affiliate patterns can be built

Round 2 — ff88d5a add callsign abbreviation map for cryptic GraceNote callsigns

• Add callsignSlugs map (280 entries) covering cable networks,
  premium movie families (Starz / MGM+ / Cinemax / Showtime / TMC),
  sports, news, kids, Spanish-language, and shopping channels. Lookup
  runs against both the raw callsign and its suffix-stripped form.
• Extend hdSuffixRe to strip HDP, HP, and standalone P (Plus
  variants)
• Iterate suffix stripping so compound suffixes collapse fully
  (MAXHDP → MAXHD → MAX)
• Add matcherVersion constant + MatcherVersion field on CacheEntry.
  Cache.Get invalidates failed entries from older matcher versions,
  forcing automatic re-check on next access. Successful matches are
  preserved across versions, so deploys don't churn already-working
  logos.

Impact

Measured against a real tvlogo_cache.json from a 616-channel lineup:

Metric	Before	After
Channels matched	142	414
Match rate	23.0%	67.2%
Failed channels	474	202

The remaining ~200 unmatched channels are predominantly foreign-language
networks (CCTV4, ZEETV, CGTN, MBCKOR, BANDAUS, TV5MOND, …), regional
sports variants without dedicated upstream logos (FDS* Bally
regionals, WNBA ION sub-feeds), and provider-specific channels like
LOOR* — all of which have no logo in the upstream repo.

Deployment notes

The matcherVersion bump from 1 → 2 means failed entries from the
old matcher auto-retry on the next scrape (~95 seconds at 5 req/sec
for ~474 misses). No manual cache wipe is required. Successful matches
from the previous matcher version are preserved.

Test plan

• Compile-checked via go build after each round
• Match rate quantified against a real tvlogo_cache.json + xmlguide.xmltv from a production GraceNote run (616 channels)
• Local-affiliate slug generation verified against the actual tv-logo/tv-logos repo manifest
• Cache version-invalidation tested: failed v1 entries return as cache misses, matched v1 entries return as cache hits
• Smoke-test on production server: deploy, force a scrape, verify match count in updated tvlogo_cache.json lands near 414