perf: optimize parse caching across providers

[spMohanty]

Summary

This PR adds a persistent, provider-agnostic parse cache so repeated runs are fast and avoid reparsing unchanged session data across CLI runs.

What changed

• Adds a persistent source cache manifest/entries with validator metadata (parser version, fingerprint paths, cache strategy, range metadata).
• Splits cache handling into two-phase planning + materialization so unchanged sources are fast-pathed.
• Improves append-style provider handling with tail/offset checks to avoid unnecessary full reparses.
• Adds provider discovery caching to skip unchanged directory scans.
• Adds --no-cache support for parse-backed commands to force full rebuild.
• Adds provider-aware cache progress reporting on stderr.
• Updates dashboard windowing to reuse cached windows and preload 30days where useful.
• Adds a small launcher shim (bin/codeburn) to harden global installs.
• Documents cache behavior in README/CHANGELOG.

Performance Impact

Benchmark command (all runs are separate CLI processes):

CODEBURN_CACHE_DIR=/tmp/codeburn-bench-<id> \
HOME=$HOME \
node --import tsx /tmp/bench-once.mjs <repo_root> all

Using the same cache directory for the repeated warm runs.

• Upstream baseline (https://github.com/getagentseal/codeburn@e259220, main):

  • cold run (empty cache directory): 45.600s
  • warm run (separate process, same cache directory): 50.606s, 49.515s, 42.975s, 35.827s, 40.916s

• Current branch (https://github.com/spMohanty/codeburn@7594fa0, dev/cache-parse-parse-performance):

  • cold run (empty cache directory): 51.904s
  • warm run (separate process, same cache directory): 4.953s, 6.548s, 4.073s, 4.264s, 4.651s

Validation

• npm test -- --testTimeout 30000 (27 test files, 329/329 tests passed)
• npm run build
• git status is clean

Notes

• Behavior remains backwards compatible: stale/incompatible cache entries are refreshed automatically.
• Warm runs are intentionally measured as separate CLI invocations to match real user usage.

[iamtoruk]

Merged, thanks SP! Great contribution.

Added one small fix on top: tightened TypeScript types (type predicates for breakdown validators, null guards on append state), removed unused exports, fixed a file descriptor leak in the offset reader, and cleaned up import ordering.

329 tests passing, cache integrity verified against no-cache output. Appreciate the thorough work on this.