feat: support nanosecond MID (phase 2)

[cheb0]

Description

Main differences with the previous PR:

• all seq.MID are now in nanoseconds.
• all new versions (frac version, meta version, etc) with nano MID are used everywhere by default.
• proxy is able to extract nanosecond time from JSON docs now.
• store protocol is now 2 which indicates that MID are sent in nanoseconds
• frac info cache stores info as json, MID are converted to milliseconds. Info now has custom JSON marshaling methods

Fixes #232

---

• I have read and followed all requirements in CONTRIBUTING.md;
• I used LLM/AI assistance to make this pull request;

[codecov-commenter]

Codecov Report

❌ Patch coverage is 67.92453% with 51 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.10%. Comparing base (602c42a) to head (a8dc1d7).

Files with missing lines	Patch %	Lines
storeapi/client.go	0.00%	25 Missing ⚠️
asyncsearcher/async_searcher.go	20.00%	4 Missing ⚠️
frac/sealed/seqids/blocks.go	77.77%	2 Missing and 2 partials ⚠️
proxy/search/async.go	57.14%	2 Missing and 1 partial ⚠️
cmd/distribution/main.go	0.00%	2 Missing ⚠️
frac/common/info.go	88.23%	1 Missing and 1 partial ⚠️
proxy/search/ingestor.go	50.00%	2 Missing ⚠️
proxy/search/streaming_doc.go	0.00%	1 Missing and 1 partial ⚠️
storeapi/grpc_search.go	66.66%	2 Missing ⚠️
frac/processor/search.go	90.90%	1 Missing ⚠️
... and 4 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #291      +/-   ##
==========================================
+ Coverage   71.05%   71.10%   +0.05%     
==========================================
  Files         201      201              
  Lines       14712    14773      +61     
==========================================
+ Hits        10454    10505      +51     
- Misses       3515     3522       +7     
- Partials      743      746       +3     

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