feat: added support for registering embedded filesystems as view sources

[protibimbok]

📑 Description

Closes goravel/goravel#990

Packages can now ship their views inside the binary with go:embed instead of
requiring template files on disk at runtime.

Added

• View.LoadViewsFromFS(fsys fs.FS, root string) — registers an fs.FS
  (e.g. an embed.FS) as a package view source. root selects the directory
  inside the FS; pass "." to use the whole FS.
• View.RegisteredViewFS() []fs.FS — returns the registered filesystems in
  registration order, for HTTP drivers to load templates from.
• Errors ViewFSRequired and ViewInvalidFSRoot (panics on a nil FS or an
  invalid root, matching how a bad path fails today).

//go:embed views/*
var views embed.FS

facades.View().LoadViewsFromFS(views, "views")

Behaviour

• Each FS is rooted with fs.Sub at registration time, so every source looks
  the same to consumers: template paths are relative to "." (e.g.
  layouts/app.tmpl), including nested directories.
• root accepts loose forms ("", ./views, /views/, views\admin) and is
  normalised to a valid io/fs path.
• Exists() also checks registered filesystems.
• Precedence is unchanged: app views > LoadViewsFrom dirs >
  LoadViewsFromFS, each in registration order. Existing LoadViewsFrom
  users are unaffected.

Notes

• The mocks/view mock is regenerated for the new interface methods.
• Actual template loading from these filesystems lands in the HTTP driver;
  a companion goravel/gin PR follows once this is tagged.

✅ Checks

• Added test cases for my code

[codecov]

Codecov Report

❌ Patch coverage is 96.96970% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 72.69%. Comparing base (cfde3ce) to head (f7d4fc1).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
view/view.go	96.96%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1546      +/-   ##
==========================================
+ Coverage   72.41%   72.69%   +0.27%     
==========================================
  Files         409      412       +3     
  Lines       26475    26772     +297     
==========================================
+ Hits        19172    19462     +290     
- Misses       7301     7308       +7     
  Partials        2        2              

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[hwbrzzl]

Thanks, checking

[protibimbok]

Not sure if you have noticed but please check goravel/gin#242 too
Both are completed and goes together

[goravel-coder]

Review

Thanks for the PR — clean, well-tested change overall. A few findings below.

Please double-confirm each finding against your local environment before resolving. Several of these (especially #1 and #2) depend on Go stdlib and OS behavior (fs.Sub validation, filepath.ToSlash) that can vary by Go version / platform, so please verify the exact behavior on your setup rather than taking them at face value.

Should Fix

1. LoadViewsFromFS never verifies the root actually exists — view/view.go:63-66

fs.Sub only enforces fs.ValidPath (rejects .././empty elements); it does not stat the directory. For embed.FS (which doesn't implement SubFS), LoadViewsFromFS(fsys, "typo") registers a silently-empty source with no error — every later fs.Stat/fs.ReadFile returns fs.ErrNotExist. This contradicts the contract doc ("panics if … root is not a valid fs path") and the ViewInvalidFSRoot name. Either fs.Stat(sub, ".") at registration and panic on ErrNotExist, or narrow the docs to "rejects ../absolute roots; nonexistent roots are accepted lazily."

2. Backslash normalization is a no-op on non-Windows — view/view.go:119

filepath.ToSlash is an identity on Linux/macOS, so the documented views\admin form is not converted there; the backslash survives as a literal path element and fs.Sub accepts it, silently registering a source rooted at a nonexistent name. The "os separator" test (view/view_test.go:92,157) is a no-op on non-Windows CI, so this is invisible to the current test matrix. Either add explicit strings.ReplaceAll(p, "\\", "/"), or drop the backslash claim from the doc comments.

3. Panic vs silent divergence between sibling methods — view/view.go:50-54 vs :56-71

LoadViewsFrom silently appends any path; LoadViewsFromFS panics on nil/invalid root. Two methods doing the same conceptual thing now fail differently. Defensible, but worth reconciling or documenting the rationale.

Nits

• view/view.go:40 — normalizeFSPath runs unconditionally on every Exists miss, even when no FS sources are registered. Guard with if len(r.filesystems) > 0.
• view/view.go:40-45 — Exists("")/Exists(".") return true once any FS is registered (fs.Stat(sub, ".") stats the root dir). Edge case; a cheap empty/dot guard closes it.
• Rendering depends on the companion driver — Exists is only half the story; actual View().Make(...) requires the gin/fiber driver to parse RegisteredViewFS(). That's deferred to a companion PR.
• contracts/view/view.go:17 — godoc example //go:embed views/* embeds only direct children; nested dirs (layouts/, partials/) need //go:embed views or views/**.
• contracts/view/view.go:23 — RegisteredViewFS reads singular next to plural RegisteredViews; consider RegisteredViewFSs.
• view/view_test.go:245-253 — setupAppViews mutates process-global support.RelativePath/support.Config.Paths.Resources; race-free today (no t.Parallel(), verified with -race) but fragile.

Verified correct

• Root-escape (../views) is correctly rejected via fs.ValidPath → fs.ErrInvalid → ViewInvalidFSRoot.
• RegisteredViews/RegisteredViewFS both make+copy; no mutation leaks.
• Mutex discipline is race-free; errors use the New(...) constructor; gofmt/go vet clean; mock regenerated correctly.