Fix Dockerfile to compile all 4 extensions

[pyramation]

Summary

Fixes the Docker build to successfully compile all 4 PostgreSQL extensions (pgvector, PostGIS, pg_textsearch, pgsodium).

Changes:

• Add perl, flex, bison build dependencies required by PostGIS (configure was failing with "Perl was not found")
• Pin pg_textsearch to v0.2.0 and add version ARG for consistency
• Patch pg_textsearch to add missing #include <math.h> (upstream bug causing build failure)

Review & Testing Checklist for Human

• Verify the math.h patch is acceptable - The sed command patches an upstream bug in pg_textsearch. This is fragile and may need updating if upstream changes. Consider whether to report this upstream.
• Run make test to verify all 4 extensions can be created:

  make test

  Expected output: all extensions OK after creating vector, postgis, pg_textsearch, and pgsodium extensions
• Note pg_textsearch is prerelease - v0.2.0 shows a warning that it's not recommended for production use

Notes

• pg_textsearch v0.2.0 displays: "This is prerelease software and should not be used in production"
• The upstream math.h bug exists in both main branch and v0.2.0 tag of timescale/pg_textsearch

Link to Devin run: https://app.devin.ai/sessions/167cadea4ff447f098e983f2a5d8d66c
Requested by: Dan Lynch (@pyramation)

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